Recording medium, recording apparatus, and reading apparatus

ABSTRACT

Within a sub-code to be recorded in a recording medium, the physical characteristics of the recording medium are recorded. This enables a recording apparatus or a reading apparatus to easily and correctly determine the physical characteristics of the recording medium by reading the sub-code. The physical characteristic information includes information concerning the material, the disc type, the linear velocity, the track pitch, the moment of inertia, and the size/configuration of the recording medium. It is thus possible to easily and correctly determine the physical characteristics of the disc (or unit area) while maintaining the compatibility with known recording media.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium, and also to arecording apparatus and a reading apparatus compatible with such arecording medium.

2. Description of the Related Art

As a recording medium, a compact disc (CD) is known. Various types ofCD-format discs, such as compact disc digital audio (CD-DA), compactdisc read only memory (CD-ROM), compact disc recordable (CD-R), compactdisc rewritable (CD-RW), and CD-TEXT, all of which belong to theso-called “CD family”, have been developed and are commonly used.

The CD-DA and CD-ROM are read only, while the CD-R is a write-oncemedium using an organic pigment on a recording layer, and the CD-RW is arewritable medium using a phase change technique.

On such CD-format discs, data, such as music, video, and computer data,are recorded, and also, track numbers, indexes, and addresses arerecorded as sub-codes.

The track number is a number representing a piece of music (track). Theindexes are units which form a track, for example, units which partitionthe movements of a track.

The addresses include absolute addresses represented by consecutivevalues covering the whole disc and relative addresses represented inunits of tracks (which are also referred to as “programs” represented inunits of pieces of music). Accordingly, by extracting sub-codes, theabsolute address and the relative address at each position of a disc canbe identified.

The address is represented by a time value, such as minute/second/frame.Thus, in the CD format, the “time” can be synonymous with the “position(address)”, for example, the “absolute time” corresponds to the“absolute address”.

For example, in the CD format, the sub-code address is represented byminute/second/frame, each having eight bits. Since the eight-bit addressis represented in binary coded decimal (BCD), it can express a rangefrom 0 to 99. Accordingly, the “minute” can be designated from 0 to 99minutes. However, the “second” is inevitably expressed from 0 to 59, andthe “frame” is expressed from 0 to 74 since 75 frames, such as frame 0to frame 74 are defined in the CD format.

On the innermost portion of a disc, sub-code information, such astable-of-content (TOC) information, is recorded. The TOC informationindicates an address representing the head and the extent of each track.The content of the address (type of address) can be identified by pointinformation.

For example, if the point information designates a special value, theinformation described in the corresponding sub-code frame indicates thestart address of each track or the first/last track number rather thanthe absolute address or the relative address.

In recordable discs, such as a CD-R and a CD-RW, a recording track isformed by wobbling grooves. The wobbling waveforms of the grooves areformed by modulating waveforms based on the absolute addressinformation, and thus, the absolute addresses can be identified by thewobbling information of the grooves. Since sub-codes are not yetrecorded on a disc without recorded data, the address information isread by the wobbling groove when data is recorded.

In addition to the above-described various types of CD-format(CD-standard) discs, larger capacity discs with high density are beingdeveloped, and discs having a plurality of areas whose physicalcharacteristics are different, which are referred to as “hybrid discs”,are also being developed. The variety of the materials andconfigurations of discs is also being increased.

Under these circumstances, in order to achieve sufficient recording andreading performance of a recording apparatus and a reading apparatus, itbecomes necessary to optimize various settings in accordance with thephysical characteristics of a loaded disc. For example, the servo gain,laser power, and access range should be optimized.

It is, however, difficult to sufficiently determine the physicalcharacteristics of the individual discs loaded in a recording apparatusor a reading apparatus. Certain calibration may be performed when a discis loaded, and even so, it is still difficult to precisely determine thephysical characteristics of the loaded disc. Additionally, since theburden is increased by the calibration operation, the amount of softwareand hardware must be increased, and also, it takes a longer time beforea recording or reading operation is started.

Accordingly, there is still a demand for easy and precise determinationof the physical characteristics of discs without impairing thecompatibility with known CD-format discs or increasing the complexity ofhardware and software used in a recording apparatus and a readingapparatus.

SUMMARY OF THE INVENTION

Accordingly, in view of the above background, it is an object of thepresent invention to easily and precisely determine the physicalcharacteristics of recording media while being compatible with varioustypes of recording media and maintaining the compatibility with knownrecording media.

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a recording medium including maindata and a sub-code recorded therein. Physical characteristicinformation of the recording medium is recorded within the sub-code.

Point information representing content types of predeterminedinformation may be disposed within the sub-code, and the physicalcharacteristic information may be recorded in correspondence withspecific values of the point information.

The physical characteristic information may be recorded within thesub-code of a lead-in area.

The physical characteristic information may include informationconcerning the material, the type, the linear velocity, the track pitch,the moment of inertia, the configuration, or the size of the recordingmedium.

According to another aspect of the present invention, there is provideda recording medium for storing main data and a sub-code. The recordingmedium includes a plurality of recording/reading unit areas whosephysical characteristics are different, each of the recording/readingunit areas consisting of a lead-in area, a program area, and a lead-outarea. In the sub-code of the lead-in area of each of therecording/reading unit areas, physical characteristic information of thecorresponding recording/reading unit area is recorded, and startposition information indicating a position at which the lead-in area ofthe subsequent recording/reading unit area starts is recorded.

In the sub-code of the lead-in area of each of the recording/readingunit areas, end position information indicating a position at which thelead-out area of the corresponding recording/reading unit area ends maybe recorded.

According to still another aspect of the present invention, there isprovided a recording apparatus compatible with a recording medium whichstores main data and a sub-code, physical characteristic information ofthe recording medium being recorded within the sub-code. The recordingapparatus includes a determining unit for determining physicalcharacteristics of the recording medium by reading the physicalcharacteristic information from the sub-code. A recording control unitperforms settings for a recording operation according to the physicalcharacteristics determined by the determining unit and then allows therecording operation to be performed.

According to a further aspect of the present invention, there isprovided a recording apparatus compatible with a recording medium whichstores main data and a sub-code, the recording medium including aplurality of recording/reading unit areas whose physical characteristicsare different, each of the recording/reading unit areas consisting of alead-in area, a program area, and a lead-out area. In the sub-code ofthe lead-in area of each of the recording/reading unit areas, physicalcharacteristic information of the corresponding recording/reading unitarea is recorded, and start position information indicating a positionat which the lead-in area of the subsequent recording/reading unit areastarts is recorded. The recording apparatus includes an access controlunit for determining the position of the lead-in area of the subsequentrecording/reading unit area from the start position information recordedin the lead-in area of the current recording/reading unit area, and forallowing access to the determined position. A determining unit reads thephysical characteristic information from the lead-in area of each of therecording/reading unit areas in accordance with the access controlled bythe access control unit, and determines the physical characteristics ofthe corresponding recording/reading unit area. A recording control unitperforms settings for a recording operation for each of therecording/reading unit areas according to the physical characteristicsdetermined by the determining unit, and allows the recording operationto be performed.

According to a yet further aspect of the present invention, there isprovided a reading apparatus compatible with a recording medium whichstores main data and a sub-code, physical characteristic information ofthe recording medium being recorded in the sub-code. The readingapparatus includes a determining unit for determining physicalcharacteristics of the recording medium by reading the physicalcharacteristic information from the sub-code. A reading control unitperforms settings for a reading operation according to the physicalcharacteristics determined by the determining unit and allows thereading operation to be performed.

According to a further aspect of the present invention, there isprovided a reading apparatus compatible with a recording medium whichstores main data and a sub-code, the recording medium including aplurality of recording/reading unit areas whose physical characteristicsare different, each of the recording/reading unit areas consisting of alead-in area, a program area, and a lead-out area. In the sub-code ofthe lead-in area of each of the recording/reading unit areas, physicalcharacteristic information of the corresponding recording/reading unitarea is recorded, and start position information indicating a positionat which the lead-in area of the subsequent recording/reading unit areastarts is recorded. The reading apparatus includes an access controlunit for determining the position of the lead-in area of the subsequentrecording/reading unit area from the start position information recordedin the lead-in area of the current recording/reading unit area, and forallowing access to the determined position. A determining unit reads thephysical characteristic information from the lead-in area of each of therecording/reading unit areas in accordance with the access controlled bythe access control unit, and determines the physical characteristics ofthe corresponding recording/reading unit area. A reading control unitperforms settings for a reading operation for each of therecording/reading unit areas according to the physical characteristicsdetermined by the determining unit and allows the reading operation tobe performed.

Thus, according to the present invention, in sub-code, the physicalcharacteristics of the recording medium are recorded. By reading thesub-code, a recording apparatus and a reading apparatus can easily andaccurately determine the physical characteristics of the disc.

It is thus possible to provide settings suitable for the recordingoperation and the reading operation, for example, the servo gain, thelaser power, the laser driving waveform, the access range of the opticalpick-up, thereby enhancing the recording and reading performanceaccording to the type of disc.

The physical characteristics of the recording medium are not determinedby a calibration operation. Theoretically, therefore, they can bedetermined with 100% precision, and the time required for starting therecording or reading operation can be shortened.

Additionally, since the physical characteristic information is recordedin correspondence with specific values of the point information withinthe sub-code, the compatibility with known format discs can bemaintained. The physical characteristic information is recorded in thesub-code of the lead-in area, which is first read when a disc is loaded,thereby enabling a recording apparatus or a reading apparatus to easilyand speedily obtain the physical information.

The material information of the recording medium is also included in thephysical characteristic information. It is thus possible to optimizevarious settings for, for example, the laser power and the laser drivingwaveform, in accordance with the material.

Since the information, such as the medium type, the linear velocity, andthe track pitch, is included in the physical characteristic information,the servo system for the recording/reading operation can be easily set,and the disc type can be easily determined.

The moment-of-inertia information and the disc configuration/sizeinformation are contained in the physical characteristic information.Accordingly, the spindle servo gain and the access range of the opticalpick-up can be precisely set.

As to a disc having a plurality of unit areas (hybrid disc) whosephysical characteristics are different, access can be easily made fromthe lead-in area of a unit area to the lead-in area of the subsequentunit area. Accordingly, a recording apparatus or a reading apparatus isable to easily and speedily read the physical characteristicsinformation of each of the unit areas, which can be used for settingsfor a subsequent recording or reading operation. That is, it is possibleto perform optimal settings according to the physical characteristic ofeach unit area, thereby enhancing the recording and reading performance.

In the sub-code of each unit area, the end position information of thelead-out area of the corresponding unit area is recorded. Accordingly,any gap between the lead-out area of the corresponding unit area and thelead-in area of the subsequent unit area can be correctly determined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1D illustrate types of discs according to an embodimentof the present invention;

FIG. 2 illustrates a standard density disc and a high density discaccording to an embodiment;

FIGS. 3A through 3C illustrate types of discs according to an embodimentof the present invention;

FIGS. 4A through 4C illustrate types of hybrid discs according to anembodiment of the present invention;

FIGS. 5A and 5B illustrate types of hybrid discs according to anembodiment of the present invention;

FIG. 6 illustrates the layout of a CD-R or CD-RW disc;

FIG. 7 illustrates a wobbling groove;

FIG. 8 illustrates ATIP encoding;

FIGS. 9 and 10 illustrate ATIP waveforms;

FIG. 11 illustrates an ATIP frame used in an embodiment of the presentinvention;

FIG. 12 illustrates the content of an ATIP frame used in an embodimentof the present invention;

FIG. 13 illustrates details of part of the ATIP frame shown in FIG. 12;

FIG. 14 illustrates material data contained in the wobble informationshown in FIG. 13;

FIG. 15 illustrates disc density data contained in the wobbleinformation shown in FIG. 13;

FIG. 16 illustrates physical structure data contained in the wobbleinformation shown in FIG. 13;

FIG. 17 illustrates disc configuration data contained in the wobbleinformation shown in FIG. 13;

FIGS. 18A and 18B illustrate circular discs represented by the discconfiguration data shown in FIG. 17;

FIGS. 19A and 19B illustrate triangular discs represented by the discconfiguration data shown in FIG. 17;

FIGS. 20A, 20B, and 20C illustrate quadrilateral discs represented bythe disc configuration shown in FIG. 17;

FIGS. 21A and 21B illustrate disc dimensions contained in the wobbleinformation shown in FIG. 13;

FIG. 22 illustrates an example of moment-of-inertia data contained inthe wobble information shown in FIG. 13;

FIG. 23 illustrates another example of the moment-of-inertia datacontained in the wobble information shown in FIG. 13;

FIG. 24 illustrates a recording area format;

FIG. 25 illustrates a track format;

FIG. 26 illustrates a disc format including fixed-length packets;

FIG. 27 illustrates the frame structure of a disc according to anembodiment of the present invention;

FIGS. 28A and 28B illustrate a sub-coding frame of a disc according toan embodiment of the present invention;

FIGS. 29A and 29B illustrate an example of sub-Q data of a discaccording to an embodiment of the present invention;

FIGS. 30A and 30B illustrate another example of the sub-Q data of a discaccording to an embodiment of the present invention;

FIG. 31 illustrates the TOC structure of a disc according to anembodiment of the present invention;

FIG. 32 illustrates an example of the content of the sub-Q data used inan embodiment of the present invention;

FIG. 33 illustrates an example of disc size information contained in thesub-Q data used in an embodiment of the present invention;

FIG. 34 illustrates an example of disc configuration informationcontained in the sub-Q data used in an embodiment of the presentinvention;

FIG. 35 illustrates an example of moment-of-inertia informationcontained in the sub-Q data used in an embodiment of the presentinvention;

FIG. 36 illustrates an example of track pitch information contained inthe sub-Q data used in an embodiment of the present invention;

FIG. 37 illustrates an example of linear velocity information containedin the sub-Q data used in an embodiment of the present invention;

FIG. 38 illustrates an example of medium type information contained inthe sub-Q data used in an embodiment of the present invention;

FIG. 39 illustrates an example of material type information contained inthe sub-Q data used in an embodiment of the present invention;

FIG. 40 illustrates another example of the content of the sub-Q dataused in an embodiment of the present invention;

FIG. 41 illustrates another example of disc size/configurationinformation contained in the sub-Q data used in an embodiment of thepresent invention;

FIG. 42 illustrates another example of track pitch information containedin the sub-Q data used in an embodiment of the present invention;

FIG. 43 illustrates another example of linear velocity informationcontained in the sub-Q data used in an embodiment of the presentinvention;

FIG. 44 illustrates another example of medium version informationcontained in the sub-Q data used in an embodiment of the presentinvention;

FIG. 45 illustrates another example of medium type information containedin the sub-Q data used in an embodiment of the present invention;

FIG. 46 illustrates the content of the sub-Q data used in an embodimentof the present invention;

FIGS. 47A and 47B illustrate access made according to the content of thesub-Q data shown in FIG. 46;

FIG. 48 is a block diagram illustrating a disc drive unit according toan embodiment of the present invention;

FIGS. 49 and 50 are flow charts illustrating the processing executed bythe disc drive unit when a disc is inserted according to an embodimentof the present invention;

FIG. 51 is a flow chart illustrating setting processing executed by thedisc drive unit according to an embodiment of the present invention;

FIG. 52 is a flow chart illustrating recording processing executed bythe disc drive unit according to an embodiment of the present invention;

FIGS. 53A and 53B are Bode diagrams illustrating the servo open loop forsetting the moment of inertia used in an embodiment of the presentinvention; and

FIG. 54 illustrates laser drive pulses used in an embodiment of thepresent invention;

FIG. 55 illustrates the layout of a DVD-RW or DVD-R disc;

FIG. 56 illustrates land pre-pits;

FIGS. 57A, 57B, and 57C illustrate the data structure formed by a landpre-pit;

FIG. 58 illustrates the field ID of the land pre-pit data;

FIG. 59 illustrates the structure of a pre-pit block of a land pre-pit;

FIGS. 60A and 60B illustrate physical characteristic informationrecorded in a land pre-pit;

FIG. 61 illustrates the layout of a DVD-RAM disc;

FIG. 62 illustrates the structure of the lead-in area of a DVD-RAM;

FIG. 63 illustrates the block structure of a control data zone of aDVD-RAM;

FIG. 64 illustrates the contents of the physical format informationaccording to an embodiment of the present invention;

FIG. 65 illustrates part of the physical format information shown inFIG. 64;

FIGS. 66A, 66B, and 66C illustrate the phase modulation of ADIP units ofa DVD+RW;

FIG. 67 illustrates an ADIP unit of a DVD+RW;

FIGS. 68A an 68B illustrate the structure of an ADIP word of a DVD+RW;and

FIGS. 69A and 69B illustrate the physical format information to berecorded in an ADIP word according to an embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described below in detail with reference to theaccompanying drawings through illustration of preferred embodiments.

Discs provided as recording media of the present invention, a disc driveunit provided as a recording apparatus and a reading apparatus of thepresent invention are discussed below in the following order.

1. Overview of CD-system signal processing

2. Types of CD-format discs

3. Recordable discs and grooves

3-1 Rewritable discs

3-2 Wobble information

3-3 Recording area format

4. Sub-code and TOC

5. Configuration of disc drive unit

6. Examples of processing of disc drive unit

7. Examples of digital versatile disc (DVD)-format discs

7-1 DVD-RW, DVD-R

7-2 DVD-RAM

7-3 DVD+RW

1. Overview of CD-system Signal Processing

A description is now given of an overview of signal processing ofCD-system discs, such as a CD-DA, a CD-ROM, a CD-R, and a CD-RW.

An overview of the CD-system signal processing, and more specifically,the recording operation of a stereo audio signal on a disc, is asfollows.

Audio signals on left and right channels (L-Ch and R-Ch) are sampled ata sampling frequency of 44.1 kHz and are then linearly quantized withsixteen bits. Sixteen bits of the audio signal data is determined to beone word, and is further divided into eight-bit data units, and eacheight-bit data is determined to be one symbol (one symbol=eight bits=½word).

Six samples for each channel, i.e., 16 bits×2 channels×6 samples=192bits=24 symbols, are extracted, and four symbols of error correctingcode (ECC) are added to 24 symbols as Q-parity, resulting in 28 symbols.In the CD system, Reed-Solomon codes are generated and added as the ECC.To handle continuous burst defects on a disc substrate, the 28-symbolaudio signal is interleaved (rearranged).

Thereafter, four symbols of Reed-Solomon codes (P-parity) are furtheradded to the 28-symbol audio signal, resulting in 32 symbols, and onesymbol for a control operation (sub-code) is further added. Theresulting signal is subjected to eight-to-fourteen modulation (EFM).According to the EFM operation, eight bits are expanded to fourteenbits.

According to the EFM operation, a 16-bit quantized signal is dividedinto upper eight bits and lower eight bits, and an eight-bit signal isset as the smallest unit and is converted into a 14-bit signal. In thiscase, the smallest number of consecutive bits is three, and the greatestnumber of consecutive bits is eleven, i.e., two to ten “0”s are insertedbetween “1”s. After conversion, “1” represents a polarity inversion (nonreturn to zero inverted (NRZ-I) recording).

According to the EFM, an eight-bit signal is converted into a 14-bitsignal in which two to ten “0”s are inserted between “1”s, and threecoupling bits are provided for satisfying the condition that at leasttwo “0”s are inserted between “1”s over adjacent symbols. Accordingly,in the EFM-modulated signals, i.e., in the recording data streams, thereare nine types of bit lengths ranging from the minimum length (time)Tmin=3T (0.9 ns) to the maximum length (time) Tmax=11T (3.3 ns).

A frame synchronization signal and a control signal, which formssub-codes, are added to the EFM modulated data (frame), and theresulting data stream is recorded on a disc. The frame synchronizationsignal and the sub-code are discussed in detail below.

Conversely, when reading the data stream recorded as described above, itis decoded in the reverse order to the recording processing. That is,the EFM demodulation is performed on a data stream read from the disc,and error correcting, deinterleaving, and channel separation are furtherperformed. Then, L and R audio data signals quantized with 16 bits andsampled at 44.1 kHz are converted into analog signals, which are thenoutput as a stereo music signal.

2. Types of CD-format Discs

The types of discs implemented as CD-format discs in this embodiment arediscussed below with reference to FIGS. 1A through 5B.

FIGS. 1A through 1D schematically illustrate the types of discs based onthe recording density. More specifically, FIG. 1A illustrates a knowndisc with a standard recording density. In this example, the whole discis recorded at a standard recording density. Currently used discs, suchas a CD-DA, a CD-ROM, a CD-R, and a CD-RW, correspond to this type ofdisc.

FIG. 1B illustrates a high density disc which has recently beendeveloped, and in this example, the whole disc can be recorded at a highdensity. For example, by comparison with the standard disc, 2× or 3×high density discs have been developed. In particular, recordable highdensity discs, such as a CD-R and a CD-RW, have been developed.

FIG. 1C illustrates a hybrid disc whose inner portion is a high densityarea and whose outer portion is a standard density area. Conversely,FIG. 1D illustrates a hybrid disc whose outer portion is a high densityarea and whose inner portion is a standard density area.

The characteristics/parameters of the standard density disc and those ofthe high density disc are shown in FIG. 2.

Concerning the capacity of user data (main data to be recorded), thestandard density disc has 650 Mbytes (disc having a diameter of 12 cm)or 195 Mbytes (disc having a diameter of 8 cm), while the high densitydisc has 1.3 Gbytes (disc having a diameter of 12 cm) or 0.4 Gbytes(disc having a diameter of 8 cm). Thus, the high density disc has acapacity twice as large as the standard density disc.

The program area start position (radius) (area at which the user data isrecorded) of the standard density disc is 50 mm from the center of thedisc, and that of the high density disc is 48 mm from the center of thedisc.

The track pitch of the standard density disc (standard density area) is1.6 μm, while that of the high density disc (high density area) is 1.1μm.

The scanning speed of the standard density disc (standard density area)is 1.2 to 1.4 m/s, while the scanning speed of the high density disc(high density area) is 0.9 m/s.

The numerical aperture (NA) for the standard density disc (standard discarea) is 0.45, while the NA for the high density disc (high densityarea) is 0.55 or 0.50.

As to the error correcting method, the cross-interleaved Reed-Solomoncode4 (CIRC4) method is employed for the standard density disc (standarddensity area), while the CIRC7 method is employed for the high densitydisc (high density area).

The characteristics and parameters other than the above-describedfactors, such as the center hole size, disc thickness, laser wavelength,modulation method, and channel bit rate, are the same, as shown in FIG.2, for the standard density disc (standard density area) and the highdensity disc (high density area).

When one of the standard density disc, such as the one shown in FIG. 1A,and the high density disc, such as the one shown in FIG. 1B, is loadedin a disc drive unit, it is necessary for the disc drive unit todetermine the type of disc.

When a hybrid disc, such as the one shown in FIG. 1C or 1D, is loaded ina disc drive unit, it is necessary for the disc drive unit to determinethe area type, i.e., whether the area on or from which data is currentlyrecorded or read, is a high density area or a standard density area.

That is, after determining the disc type or the area type, the settingof the recording/reading operation is changed in accordance with thedesignated parameters shown in FIG. 2.

FIGS. 3A through 4C schematically illustrate disc types according todata recording/reading systems.

FIG. 3A illustrates a read only disc, such as a CD-DA or a CD-ROM, whichis a disc on which all the data is recorded in an embossed bit form.

FIG. 3B illustrates a direct read after write (DRAW) disc, such as aCD-R. In this DRAW disc, a recording layer is formed of an organicpigment, and data is recorded by utilizing a change in the pigment(change in the index of reflection) caused by the irradiation with laserlight. Such a DRAW disc is also referred to as a “write-once, read-manydisc (WORM)” disc since it can be recorded to only once.

FIG. 3C illustrates a rewritable disc utilizing a phase changetechnique, such as a CD-RW.

In the DRAW (WORM) disc shown in FIG. 3B and the rewritable disc shownin FIG. 3C, the recording track is formed by a spiral groove. Incontrast, in the read only disc shown in FIG. 3A, the recording track isformed by an embossed pit stream rather than a groove.

As is described in detail below, grooves in the DRAW (WORM) disc andrewritable disc wobble (meander), which makes it possible to expressinformation, such as absolute addresses. Accordingly, in recording data,tracking control is performed on the wobbling groove, and based on thedata, such as addresses, read from the wobbling groove (hereinaftersometimes referred to as “wobble information”), the recording operationcan be controlled.

In contrast, in read only discs, a recording track is formed by a pitstream in advance, and data, such as addresses, is recorded bysub-codes. Thus, the provision of groove data is unnecessary.Accordingly, some read-only disc drive units are not provided with afunction of reading groove information.

FIGS. 4A, 4B, and 4C illustrate hybrid discs. More specifically, FIG. 4Aillustrates a disc whose inner portion is a read only area and whoseouter portion is a DRAW (WORM) area. FIG. 4B illustrates a disc whoseinner portion is a rewritable area and whose outer portion is a readonly area. FIG. 4C illustrates a disc whose inner portion is a DRAW(WORM) area and whose outer portion is a rewritable area.

Accordingly, a hybrid disc, that is, a single disc having a mixture ofdifferent areas, such as a read only area, a DRAW (WORM) area, and arewritable area, is available.

A hybrid disc having three areas may also be considered, though it isnot shown. For example, there may be a hybrid disc whose inner portionis a read only area, whose intermediate portion is a DRAW (WORM) area,and whose outer portion is a rewritable area, or a hybrid disc whoseinner portion is read only area, whose intermediate area is a rewritablearea, and whose outer area is a read only area. A hybrid disc havingfour or more areas is also possible.

As discussed above, discs can be differentiated according to therecording density or the recording/reading types, that is, according tothe physical characteristics. The types of discs can be summarized asshown in FIGS. 5A and 5B.

FIG. 5A illustrates the regular disc type, namely, the whole disc isformed of an area having one physical characteristic (“regular disc”means that disc is not a hybrid disc). Considering that there are twotypes of recording densities, such as the standard density and highdensity, and there are three recording/reading types, such as the readonly type, DRAW (WORM) type, and rewritable type, six types of discs,type 1 through type 6, can be considered, as shown in FIG. 5A.

FIG. 5B illustrates the types of hybrid discs, each having two areaswhose physical characteristics are different. By utilizing type 1 totype 6 shown in FIG. 5A, 30 types of hybrid discs, from type HD1 whoseinner portion is type 1 and whose outer portion is type 2 to type HD30whose inner portion is type 6 and whose outer portion is type 5, can beconsidered.

Apparently, if hybrid discs, each having three or more areas whosephysical characteristics are different, are considered, more types ofdiscs are available.

Along with such a variety of discs in view of the physicalcharacteristics, it is necessary for a disc drive unit to preciselydetermine the physical characteristics of a loaded disc (or physicalcharacteristics of an area on or from which data is to be recorded orread) and to perform processing according to the determined physicalcharacteristics. Then, the recording/reading performance can beenhanced.

Generally, a “disc” is a disc-shaped medium. As is discussed below,however, a triangular “disc” or a quadrilateral “disc” may be provided.Although such “discs” may sound contradictory in view of the shape of a“disc”, media other than disc-shaped media are also referred to as“discs” in this specification.

3. Recordable Discs and Grooves

3-1 Rewritable Discs

Generally, a CD-system disc has a single spiral recording track startingfrom the center (inner periphery) of the disc to the end (outerperiphery) of the disc.

On a disc on which data can be recorded by a user, such as a CD-R or aCD-RW, only a guide groove for guiding laser light is formed on a discsubstrate as a recording track before data is recorded on the disc. Whenlaser light modulated with high power is applied to the disc, the indexof reflection or the phase of the recording layer is changed, therebymaking it possible to record data on the disc. In contrast, a groove asa recording track is not physically formed on a read only disc, such asa CD-DA or a CD-ROM.

On a CD-R, a write-once recording layer, which is formed of an organicpigment, is formed. High-power laser light is applied to the disc,thereby making it possible to record data by punching (making pits onthe disc).

Regarding a rewritable disc, such as a CD-RW, whose recording layer canbe rewritten many times, a phase change technique is employed forrecording data, and more specifically, data is recorded by utilizing adifference in the index of reflection between a crystalline state and anamorphous state.

In terms of physical characteristics, the index of reflection of aCD-ROM and a CD-R is 0.7 or higher, while that of a CD-RW is as low asabout 0.2. Accordingly, in a reading apparatus designed to be compatiblewith the index of reflection of 0.7 or higher, a CD-RW cannot be read inthat apparatus. Thus, an auto gain control (AGC) function of amplifyinga low signal is added to such a reading apparatus.

In a CD-ROM, the lead-in area at the inner periphery of the disc isdisposed in a range from 46 to 50 mm from the center of the disc, andthere are no pits farther inwards than the lead-in area.

In contrast, in a CD-R and a CD-RW, a program memory area (PMA) and apower calibration area (PCA) are provided, as shown in FIG. 6, fartherinwards than the lead-in area.

The lead-in area and the subsequent program area, which is used forrecording user data, are used for performing a recording operation by adrive unit compatible with a CD-R or a CD-RW, and are also used forreading data therefrom, as in a CD-DA.

In the PMA, a recording signal mode and time information of each track,such as the start time and the end time, are temporarily stored. Whenall the tracks become full with the recorded data, the TOC is formed inthe lead-in area based on the data stored in the PMA. The PCA is an areain which data is temporarily written in order to obtain the optimalvalue of laser power when data is recorded.

In a CD-R and a CD-RW, in order to control the recording position andthe rotation of a spindle, a groove (guide groove), which is to form adata track, is formed in a wobbling (meandering) shape.

This wobbling groove is formed based on a signal modulated byinformation, such as absolute addresses. That is, wobble information,such as absolute addresses, can be read from the wobbling groove. Theabsolute time (address) information represented by the wobbling grooveis referred to as “absolute time in pregroove (ATIP)”.

The wobbling groove is wobbling slightly in a sinusoidal waveform, asshown in FIG. 7, and the center frequency of the groove is 22.05 kHz andthe amount of wobbling is approximately ±0.03 μm.

In this embodiment, in the wobbling groove, not only absolute timeinformation, but also other types of information, are encoded byfrequency modulation (FM). Details of the wobble information representedby the wobbling groove are given below.

3-2 Wobble Information

According to the wobble information detected at a push-pull channel froma CD-R/CD-RW groove, when the rotation of the spindle motor iscontrolled so that the center frequency of the wobble informationbecomes 22.05 kHz, the spindle motor is rotated at a linear velocitydefined in the CD system (for example, 1.2 to 1.4 m/s for a standarddensity disc).

For a CD-DA or a CD-ROM, the absolute time information encoded insub-code Q can be relied upon. In a CD-R or a CD-RW without datarecorded thereon (blank disc), however, sub-code is not yet recorded,and thus, the absolute time information is obtained from the wobbleinformation.

One sector (ATIP sector) of the wobble information is equivalent to onedata sector (2352 bytes) of the main channel after data is recorded on adisc. Thus, the recording operation is performed while providingsynchronization of the ATIP sector with the data sector.

The ATIP information is not encoded in the wobble information as it is.Instead, it is first subjected to bi-phase modulation, as shown in FIG.8, and then to phase modulation (FM). This is because the wobble signalis also used for controlling the rotation of the spindle motor. Morespecifically, according to the bi-phase modulation, 1 and 0 alternate atpredetermined intervals so that the ratio of the numbers of 1's and 0'sbecomes 1:1 and the average frequency of the FM-modulated wobble signalbecomes 22.05 kHz.

As will be discussed in detail below, not only the time information, butalso special information, such as information for setting the recordinglaser power, is encoded in the wobble information. In a CD-RW, byexpanding the special information, power and recording pulse informationfor the CD-RW is encoded.

FIG. 11 illustrates the configuration of one ATIP frame of the wobbleinformation.

The ATIP frame is formed of 42 bits, as indicated by (a) of FIG. 11, andis sequentially provided with a four-bit synchronization pattern, athree-bit discriminator (identifier), 21-bit wobble information, such asthe physical frame address, and a 14-bit cyclic redundancy check (CRC)code.

Alternatively, in some ATIP frames, a four-bit discriminator and 20-bitwobble information may be provided, as indicated by (b) of FIG. 11.

As the synchronization pattern disposed at the head of the ATIP frame,“11100011” is provided when the preceding bit is 0, as show in FIG. 9,and “00011101” is provided when the preceding bit is 1, as shown in FIG.10.

The three- or four-bit discriminator is an identifier indicating thecontent of the subsequent 20- or 21-bit wobble information, and isdefined as shown in FIG. 12.

The 24 bits from bits M23 to M0 shown in FIG. 12 correspond to the 24bits at bit positions 5 to 28 shown in FIG. 11.

Bits M23, M22, and M21 (or bits M23, M22, M21, and M20) are used for thediscriminator. When the value of the discriminator is “000”, the contentof the wobble information (M20 to M0) of the corresponding frameindicates the addresses of, the lead-in area, the program area, and thelead-out area. When the value of the discriminator is “100”, the contentof the wobble information (M20 to M0) of the corresponding frameindicates the address of the lead-in area. The above-mentioned addressescorrespond to absolute addresses as the above-described ATIP. The timedomain information as the ATIP is recorded radially outward startingfrom the head of the program area so that it simply increments, and isused for controlling the addresses during the recording operation.

When the value of the discriminator is “101”, the wobble information(M20 to MO) of the frame indicates special information 1. When the valueof the discriminator is “110”, the wobble information (M20 to M0) of theframe indicates special information 2. When the value of thediscriminator is “111”, the wobble information (M20 to M0) of the framerepresents special information 3.

When four bits are used for the discriminator, and its value is “0010”,the wobble information (M19 to M0) of the frame indicates specialinformation 4.

When the value of the discriminator is “010”, the wobble information(M20 to M0) of the frame indicates additional information 1. When thevalue of the discriminator is “011”, the wobble information (M20 to M0)of the frame indicates additional information 2. When four bits are usedfor the discriminator, and its value is “0011”, the wobble information(M19 to M0) of the frame represents supplemental information. Thediscriminators “1000” and “1001” are reserved for copyright informationin which copyright protection code is filled.

The contents of special information 1 to 4, additional information 1 and2, and supplemental information are shown in FIG. 13.

Special information 1 includes a four-bit target recording power, athree-bit reference velocity, a seven-bit disc application code, aone-bit disc type, and a three-bit disc sub-type. Three-bit reserve is areserved area for expanding data in the future.

As the target recording power, the laser power level at the referencevelocity is recorded. As the disc application code, the purpose of use,such as general business purpose, specific application (for example,photo-CD or karaoke CD), or commercial audio, is recorded. As the disctype, for example, “0” represents a DRAW (WORM) disc, while “1”indicates a rewritable disc. The disc sub-type represents the rotationalvelocity and constant angular velocity (CAV)/constant linear velocity(CLV).

Special information 2 includes the start address of the lead-in area.Special information 3 includes the start address of the lead-out area.

Special information 4 contains a manufacturer code, product type, andmaterial code. The name of the disc manufacturer is recorded as themanufacture code. The type of product (type number, product code, etc.)manufactured by the manufacturer is recorded as the product type. In thematerial code, the material of the recording layer of the disc isrecorded.

Details of the information of the three-bit material code are shown inFIG. 14.

Material code “000” indicates that the material is cyanine. Materialcode “001” represents that the material is phthalocyanine. Material code“010” indicates that the material is an azo compound. Theabove-mentioned materials are organic pigments for a CD-R.

In contrast, material code “100” designates a material for phase changemedia.

Normally, the material of the recording layer of a disc can bedetermined by the manufacturer code and the product type. This is basedon a system of the media manufacturing field in which the products andthe materials are registered in correspondence with each other.

That is, by storing the registered information in a disc drive unit, thematerial of the recording layer of a loaded disc can be identified fromthe manufacturer code and the product type.

However, if new discs are registered, or if discs of non-registeredproduct types or discs manufactured by non-registered manufacturers areloaded after the disc drive unit has been manufactured, the disk driveunit is unable to determine the material of the disc.

Thus, by the provision of the material code as discussed above, the discdrive unit is able to correctly determine the material of a loaded discregardless of the registration status.

Accordingly, various settings, such as laser power and laser emittingpattern, can be made according to the type of material, therebyachieving a high-precision recording operation.

Even when the material of a loaded disc can be determined from themanufacturer code and the product type, the material code may be usedfor confirming the determination result.

Additional information 1 includes, as shown in FIG. 13, informationconcerning the rotation of the spindle motor and laser power control,such as the lowest CLV recording velocity, the highest CLV recordingvelocity, power multiplication factor ρ, target γ value, anderasing/recording power ratio.

Additional information 2 also contains information concerning therotation of the spindle motor and laser power control, such as targetrecording power at the lowest recording velocity and that at the highestrecording velocity, the power multiplication factor ρ at the lowestrecording velocity and that at the highest recording velocity, and theerasing/recording power ratio at the lowest recording velocity and thatat the highest recording velocity.

The supplemental information includes inertia (moment of inertia), discconfiguration, physical structure, disc density, and so on.

Details of the one-bit disc density information are shown in FIG. 15.

The value “0” indicates that the disc density is the standard density(single density), while the value “1” designates that the disc densityis the high density (double density). By determining the type of discdensity, the characteristics and parameters of the disc can beidentified by the table shown in FIG. 2.

Details of the two-bit physical structure information are shown in FIG.16.

The value “0” indicates that a loaded disc is a regular recordable disc,while the value “1” is reserved.

Details of the two-bit disc configuration information are shown in FIG.17.

The value “00” indicates a regular (circular) disc, which is a 12-cmdisc or an 8-cm disc. The value “01” designates a triangular disc. Thevalue “10” indicates a quadrilateral disc. The value “11” represents adisc having a configuration other than the above-described discs.

Examples of the disc configuration are shown in FIGS. 18A through 20C.

FIG. 18A illustrates a 12-cm regular disc and FIG. 18B illustrates an8-cm regular disc. The diameter of the center hole CH is 15 mm. In FIGS.18A through 20C, the access range AC is a range accessible by an opticalpick-up of a disc drive unit, in other words, the radial range in whicha recording track can be formed.

Although some discs are configured differently from the above-mentionedregular discs, they can be loaded, and the recording/reading operationcan be performed on such discs as long as the size and the configurationof the discs can be accommodated within a 12-cm circular disc and thecenter hole CH has a 15-cm diameter.

FIGS. 19A and 19B illustrate triangular discs represented by the value“01” of the disc configuration. More specifically, FIG. 19A illustratesa regular triangular disc, and FIG. 19B illustrates another triangularshape other than the regular triangle. The diameter of the center holeCH of such triangular discs is 15 mm.

The access range AC of such triangular discs is smaller than that ofregular discs, as shown in FIGS. 19A and 19B. Yet, the triangular discscan be loaded in a disc drive unit and can be used for recording orreading data.

FIGS. 20A, 20B, and 20C illustrate quadrilateral discs represented bythe value “10” of the disc configuration. More specifically, FIG. 20Aillustrates a square disc, FIG. 20B illustrates a rectangular disc, andFIG. 20C illustrates another type of quadrilateral disc. The diameter ofsuch quadrilateral discs is 15 mm.

As in the triangular discs, the access range AC of such quadrilateraldiscs is smaller than that of regular discs. However, the quadrilateraldiscs can still be loaded in a disc drive unit and can be used forrecording or reading data.

Discs having configurations other than triangles and quadrilaterals,represented by the value “11” of the disc configuration, are not shown.In this case, however, pentagonal or hexagonal discs, or discs havingmore than six sides, or circular discs having a diameter other than 8 or12 cm, elliptical discs, specifically configured discs, such asstar-shaped discs or cloud-shaped discs, can be considered.

Such discs can also be used for recording or reading data as long as thesize and the configuration of such discs can be accommodated within a12-cm diameter disc and the center hole CH is 15 mm.

As indicated by the examples of triangular and quadrilateral discs shownin FIGS. 19A through 20C, they are not limited to regular triangles orsquares. Thus, if it is desired that the configuration of such discs beaccurately identified, the dimensions of such discs may be recorded in,for example, part of the reserved area (M19 to M7) of the supplementalinformation.

Alternatively, as bits representing “a” and “h” shown in FIGS. 21A and21B, four bits may be used for each of “a” and “h” as follows.

When the four-bit value indicating “a” is represented by Av and thefour-bit value indicating “h” is represented by Hv,

a=Av [mm] (0 to 15 mm are indicated in increments of 1 mm)

h=Hv/10 (0 to 1.5 mm are indicated in increments of 0.1 mm).

Details of the two-bit inertia (moment of inertia) of the supplementalinformation are shown in FIG. 22.

When the value of inertia is “00”, the moment of inertia is less than0.01 g·m². When the value of inertia is “01”, the moment of inertia is0.01 g·m² or greater but less than 0.02 g·m². When the value of inertiais “10”, the moment of inertia is 0.02 g·m² or greater but less than0.03 g·m². When the value of inertia is “11”, the moment of inertia is0.03 g·m² or greater.

When the moment of inertia is represented by J, it is expressed by thefollowing equation:

J=Σ(m _(i) ×r _(i) ²)

wherein r_(i) represents the distance from the origin (i.e., the centerof the rotation of the disc), and m_(i) designates a minute mass at theposition r_(i).

According to the above-described equation, the moment of inertia J isthe sum of the product of the minute mass m_(i) and the squared distancer_(i), and never becomes zero. Accordingly, with a larger disc, themoment of inertia J is increased.

The physical meaning of the moment of inertia J is an amount expressedin an equation of the rotation. That is, the following equation holdstrue:

J×α=T

wherein α represents a second-order differential of the rotational angleθ (=angular velocity), and T designates the moment of force (torque).

This equation reveals that the moment of inertia J is equivalent to themass m in an equation of the particle rotation. That is, the moment ofinertia J is an important physical mass in terms of the rotation of arigid material.

Generally, the imbalance I_(m) of a disc is expressed by the followingequation.

 I _(m)=Σ(m _(i) ×r _(i))

That is, the imbalance I_(m) is the sum of the product of the minutemass m_(i) and the squared distance r_(i). If a disc is perfectlysymmetrical and free from non-uniformities in the thickness, theimbalance I_(m) is zero. However, although the imbalance I_(m) is zero,the moment of inertia J is not zero, and there is no correlation betweenthe moment of inertia J and the imbalance I_(m).

As is seen from the foregoing description, the moment of inertia of adisc is used for controlling a spindle motor which rotates a disc.

As discussed above, discs are not restricted to 8- or 12-cm circulardiscs, and there are various configurations and sizes of discs. Themoment of inertia of a disc is different according to the size andconfiguration of the disc. Accordingly, by providing the moment ofinertia, as discussed above, the rotation driving system of the spindlemotor can be controlled correspondingly (i.e., according to the size andconfiguration of the disc). More specifically, the optimal spindle-servogain can be set according to the size and configuration of the disc.

Although in this embodiment the moment of inertia is represented by twobits, it may be expanded to three bits by using bit M7 for the reservedarea of the supplemental information. In this case, the moment ofinertia may be represented as shown in FIG. 23.

The value “000” indicates that the moment of inertia is less than 0.004g·m². The value “001” indicates that the moment of inertia is 0.004 g·m²or greater but less than 0.01 g·m². The value “010” indicates that themoment of inertia is 0.01 g·m² or greater but less than 0.022 g·m². Thevalue “011” indicates that the moment of inertia is 0.022 g·m² orgreater but less than 0.032 g·m². The value “100” indicates that themoment of inertia is 0.032 g·m² or greater but less than 0.037 g·m². Thevalue “101” indicates that the moment of inertia is 0.037 g·m² orgreater. The values “110” and “111” are reserved. If a greater value ofthe moment of inertia is expected, the above-described definition iseffective.

As a example, considering the standard thickness, configuration, andmass (material), a 60-mm disc has a moment of inertia equivalent to“000”, an 80-mm disc has a moment of inertia equivalent to “001”, a100-mm disc has a moment of inertia equivalent to “010”, and a 120-mmdisc has a moment of inertia equivalent to “011”. The moment of inertiaof some 120-mm discs may be “100” according to the type of material. Adisc having a thickness larger than the standards, or a disc having anon-uniform mass distribution in the radial direction, for example, adisc in which the mass on the outer periphery is larger than that of theinner periphery, may have a moment of inertia equivalent to “101”.

In the examples shown in FIGS. 22 and 23, the moment of inertia isrepresented by the predetermined ranges. However, the moment of inertiamay be found by an equation, in which case, the correspondinginformation is recorded.

For example, inertia information is recorded by using four bits, such asM5 to M8. When the four-bit value is represented by J_(v) [hex], J_(cal)[g·m²] (moment of inertia) may be expressed by the following equation.

J _(cal) =J _(val)×(1/500)

Details of the wobble information contained in the ATIP frame have thusbeen discussed.

In the foregoing example, the value “00” of the disc configurationindicates both 8- and 12-cm regular (circular) discs, and they are notdifferentiated. This is because they can be differentiated by referringto the value of the moment of inertia.

More specifically, the moment of inertia of an 8-cm regular disc is lessthan 0.01 g·m², while that of a 12-cm regular disc is 0.03 g·m² orgreater. Accordingly, if the value of the disc configuration is “00” andthe value of inertia is “00”, the disc is an 8-cm regular disc.Conversely, if the value of the disc configuration is “00” and the valueof inertia is “11”, the disc is a 12-cm regular disc.

Alternatively, by using part of the reserved area of the supplementalinformation, information for differentiating an 8-cm disc and a 12-cmdisc may be recorded.

3-3 Recording Area Format

A description is now given of the format when a disc drive unit recordsdata in a recording area of a recordable optical disc. FIG. 24illustrates the format of a recording area of a recordable optical disc,and FIG. 25 illustrates the format of a track shown in FIG. 24.

The disc drive unit sequentially formats the recording area, as shown inFIG. 24, such as the PCA, the PMA, the lead-in area, one or a pluralityof tracks, and the lead-out area from the inner periphery to the outerperiphery of the disc.

Then, the disc drive unit partitions, as shown in FIG. 25, each trackinto a plurality of packets according to the packet write method, andrecords user data thereon.

The PCA shown in FIG. 24 is an area in which test-recording is performedfor adjusting the output power of laser light. Each track is an area inwhich user data is recorded. The lead-in area and the lead-out areastore the TOC, such as the start address and the end address of eachtrack, and various items of information concerning the correspondingoptical disc, respectively. The PMA is an area in which the TOC of eachtrack is temporarily stored. Each track is formed of a pre-gap forrecording track information and a user data area for recording userdata.

Each packet shown in FIG. 25 includes at least one readable user datablock, five linking blocks, which are formed of one link block and fourrun-in blocks, disposed before the user data block, and two linkingblocks formed of two run-out blocks disposed after the user data block.The link block is used for coupling packets.

According to the fixed-length packet write method, a plurality of tracksare formed in a recording area of a rewritable disc, and each track isdivided into a plurality of packets. Then, the number of user datablocks (block length) is made the same among the packets within onetrack, and data is recorded at one time in each packet.

Thus, according to the fixed-length packet write method, the recordingarea is formatted in such a manner that the packet length of theindividual packets within one track is the same, and the number of userdata blocks is the same among the packets.

FIG. 26 illustrates the format of a recording area of an optical discformatted by a disc drive unit. By wholly or partially formatting thepre-format recording area with fixed-length packets, the formattedrecording area is filled with the fixed-length packets.

4. Sub-code and TOC

The TOC and sub-code recorded on the lead-in area of a CD-format discare as follows.

The minimum unit of data recordable on a CD-format disc is a frame.Ninety-eight frames form one block. The structure of one frame is shownin FIG. 27.

One frame is formed of 588 bits in which the first 24 bits aresynchronization data, the subsequent 14 bits are sub-code data, and theremaining bits are data and parity.

The 98 frames configured as described above form one block, and sub-codedata extracted from the 98 frames are collected so as to form sub-codedata (sub-coding frame) of one block, as shown in FIG. 28A.

The sub-code data extracted from the first and second frames (frame98n+1 and 98n+2) of the 98 frames are used as synchronization patterns.The third through 98th frames (frames 98n+3 through 98n+98) form aplurality of items of channel data, i.e., sub-code data P, Q, R, S, T,U, V, and W, each having 96 bits, are formed.

Among these sub-code data, the P channel and Q channel are used forcontrolling access. However, since the P channel merely indicates apause between tracks, more precise control is performed by the Q channel(Q1 through Q96). The 96-bit Q channel data is configured as shown inFIG. 28B.

The four bits, i.e., Q1 through Q4, are used as control data foridentifying whether the number of audio channels is two or four, whetheremphasis processing has been executed on the data (music) recorded onthe disc, whether the disc is a CD-ROM, and whether digital copying isallowed.

Then, the subsequent four bits, i.e., Q5 through Q8, are used as (ADR),which indicates the mode of sub-Q data. More specifically, the followingmodes (content of sub-Q data) can be represented by the four-bit ADR.

0000: mode 0 . . . basically, all the sub-Q data is zero (except forCD-RW)

0001: mode 1 . . . normal mode

0010: mode 2 . . . catalog number of disc

0011: mode 3 . . . International Standard Recording Code (ISRC)

0100: mode 4 . . . used for CD-V

0101: mode 5 . . . used for multi-session type, such as CD-R, CD-RW, andCD-EXTRA

After the ADR, the 72 bits Q9 through Q80 are used as sub-Q data, andthe remaining Q81 through Q96 are used as a CRC.

Addresses (absolute addresses and relative addresses) can be expressedby the sub-Q data when the ADR represents mode 1.

Concerning the address formats represented by the sub-Q data, the formatemployed for known standard density discs, such as CD-DA, is discussedbelow with reference to FIGS. 29A and 29B, while the format employed forhigh density discs, such as CD-R and CD-RW, is discussed below withreference to FIGS. 30A and 30B. In the high density mode, it isnecessary to expand the maximum value of the absolute address along witha larger capacity of discs. Accordingly, the address value of the highdensity discs is represented by hour/minute/second/frame, while that ofthe standard density discs is represented by minute/second/frame.

The sub-Q data when the ADR is mode 1 is described below with referenceto FIGS. 29A through 30B, and the TOC structure of the sub-Q data isdiscussed below with reference to FIG. 31.

The sub-Q data stored in the lead-in area of a disc serves as the TOCinformation. That is, the 72-bit sub-Q data from Q9 to Q80 of the Qchannel data read from the lead-in area contains information shown inFIG. 29A or 30A. The sub-Q data shown in FIG. 29A or 30A providesdetails of the 72-bit sub-Q data (Q9 through Q80) of the Q channel datashown in FIG. 28B. The sub-Q data is divided into eight-bit portions andrepresents the TOC information.

In the sub-Q data for the standard density disc shown in FIG. 29A, theeight bits Q9 through Q16 designate the track number (TNO). In thelead-in area, the track number is set to “00”.

The subsequent eight bits Q17 through Q24 indicate point (POINT). Q25through Q32, Q33 through Q40, and Q41 through Q48, each having eightbits, represent the minute (MIN), the second (SEC), and the frame(FRAME), respectively as the absolute address. “00000000” is set in Q49through Q56. Further, PMIN, PSEC, PFRAME are recorded in Q57 throughQ64, Q65 through Q72, and Q73 through Q80, respectively. The meanings ofPMIN, PSEC, and PFRAME are determined by the value of POINT.

On the other hand, in the sub-Q code for the high density disc shown inFIG. 30A, by using each four bits of the eight bits of Q49 through Q56,the “time”, which is a higher concept than the minute/second/frame, isindicated.

More specifically, in the lead-in area, by using the four bits Q49, Q50,Q51, and Q52, the time “HOUR”, which is a higher concept than the “MIN”,“SEC”, and “FRAME”, is recorded. By using the remaining four bits Q53,Q54, Q55, and Q56, the time “PHOUR”, which is higher concept than the“PMIN”, “PSEC”, and “PFRAME”, is recorded.

In the sub-Q data of the lead-in area shown in FIG. 29A or 30A, thefollowing information is defined by the value of the point (POINT).

In the sub-Q code shown in FIG. 29A, when the value of POINT isrepresented by “01” through “9F” in BCD (or is represented by “01”through “FF” in binary code), it means the track number. In this case,in the PMIN, PSEC, and PFRAME, the minute (PMIN), the second (PSEC), andthe frame (PFRAME) of the start point (absolute time address) of thetrack number are recorded.

When the POINT value is “A0”, the track number of the first track in theprogram area is recorded in PMIN. The specification (type) of disc, suchas CD-DA, CD-Interactive (CD-I), CD-ROM (XA specifications), can beidentified by the value of PSEC.

When the POINT value is “A1”, the track number of the final track in theprogram area is recorded in PMIN.

When the POINT value is “A2”, the start point of the lead-out area isrecorded in PMIN, PSEC, and PFRAME as the absolute time address (minute(PMIN), second (PSEC), frame (PFRAME)).

On the other hand, in the sub-Q code shown in FIG. 30A, when the POINTvalue is designated by “01” through “9F”, it means the track number. Inthis case, in PHOUR, PMIN, PSEC, and PFRAME, the start point (absolutetime address) of the track number is recorded as the hour (PHOUR), theminute (PMIN), the second (PSEC), and the frame (PFRAME).

When the POINT value is “A0”, the track number of the first track in theprogram area is recorded in PMIN, and the session format can beidentified by the PSEC value. For the normal high density discs, PSEC isset to “00”.

When the POINT value is “A1”, the track number of the final track in theprogram area is recorded in PMIN.

When the POINT value is “A2”, in PHOUR, PMIN, PSEC, and PFRAME, thestart point of the lead-out area is recorded as the absolute timeaddress (hour (PHOUR), minute (PMIN), second (PSEC), and frame(PFRAME)).

As the POINT values, values which have already been defined or to bedefined in the future, such as “A3” and the subsequent values, forexample, “B*”, and “C*”, are considered. An explanation of such values,however, is omitted.

In this embodiment, various types of physical information are recordedwhen the POINT value is “F0”, and an explanation thereof is given indetail below.

Thus, the TOC is formed by the sub-Q data shown in FIG. 29A or 30A. Forexample, the TOC formed by the sub-Q data of a disc on which six tracksare recorded on the program area can be indicated by the one shown inFIG. 31.

All the track numbers TNO-of the TOC are inevitably represented by “00”.As stated above, the block number indicates the number of the sub-Q datawhich is read as the block data (sub-coding frame) formed of 98 frames.

In the TOC data, as shown in FIG. 31, the same data is recorded overthree consecutive blocks. The values of POINT “01” through “06” areindicated for six tracks (pieces of music), tracks #1 through #6,respectively, and the start points of the first track #1 through sixthtrack #6 are indicated in PHOUR, PMIN, PSEC, and PFRAME. The TOC shownin FIG. 31 is based on the sub-Q data shown in FIG. 30A, and if a TOC iscreated based on the sub-Q data shown in FIG. 29A, PHOUR is notprovided.

When the value of POINT is “A0”, “01” is indicated in PMIN as the firsttrack number. The type of disc can be identified by the PSEC value, andsince the PSEC value is “20”, the disc is a high density CD.

When the POINT value is “A1”, the track number of the final track (“06”)is recorded in PMIN. When the POINT value is “A2”, the start point ofthe lead-out area is recorded in PHOUR, PMIN, PSEC, and PFRAME.

After the block n+26 (blocks n+27 and so on), the same data indicatedfor the blocks n through n+26 is repeated.

In the example shown in FIG. 31, only six tracks are recorded, and thenumber of blocks is limited so that the POINT value designates only“A0”, “A1”, and “A2”. In practice, however, there may be more blocks sothat the value of POINT designates “A3” and the subsequent values, forexample, “F0” or “CF”, which is discussed in detail below. The number oftracks may also be different among discs. Accordingly, one unit of TOCdata is not restricted to 27 blocks shown in FIG. 31.

In the program area in which pieces of music, for example, tracks #1through #n, are stored, and in the lead-out area, the sub-Q data isindicated by the information shown in FIG. 29B or FIG. 30B.

FIG. 29B or 30B provides details of the 72-bit sub-Q data (Q9 throughQ80) of the Q channel data (Q1 through Q96) shown in FIG. 28B.

In the sub-Q data shown in FIG. 29B, eight bits Q9 through Q16 are usedfor recording the track number (TNO). That is, in the tracks #1 through#n, one of the values “01” to “99” in BCD is recorded. In the lead-outarea, “AA” is recorded in the track number.

The subsequent eight bits Q17 through Q24 are used for recording theindex (X). The index can be used for dividing each track.

Q25 through Q32, Q33 through Q40, and Q41 through Q48, each having eightbits, represent MIN (minute), SEC (second), and FRAME (frame) as thetime elapsed (relative address) within the track. “00000000” is set inQ49 through Q56.

In Q57 through Q64, Q65 through Q72, and Q73 through Q80, each havingeight bits, AMIN, ASEC, and AFRAME, are respectively recorded as theminute, second, and frame of the absolute address. The absoluteaddresses are addresses successively provided from the head of the firsttrack (i.e., the head of the program area) to the lead-out area.

Conversely, for the sub-Q data shown in FIG. 30B, the track number (TNO)is recorded in the eight bits Q9 through Q16. In the tracks #1 through#n, one of the values “01” through “9F” in binary code is indicated. Interms of decimal notation, “0” through “159” can be recorded, and thus,track numbers up to 159 can be provided. In the lead-out area, “AA” isrecorded.

In the subsequent eight bits Q17 through Q24, the index (X) is recorded.By using the index, each track can be divided into smaller portions. Asthe index number, one of the values “01” through “9F” in binary code isused.

In Q25 through Q32, Q33 through Q40, and Q41 through Q48, each havingeight bits, MIN, SEC, and FRAME are indicated as the time elapsed(relative address) within the track.

By using the subsequent four bits Q49 through Q52, the time “HOUR”,which is a higher concept than “MIN”, “SEC”, and “FRAME”, is recorded.Accordingly, the relative address is represented byhour/minute/second/frame. For data discs, hFF, FF, FF, F are used for“MIN”, “SEC”, “FRAME”, and “HOUR”, so that the relative time is notemployed.

In Q57 through Q64, Q65 through Q72, and Q73 through Q80, each havingeight bits, AMIN, ASEC, and AFRAME, respectively, are recorded as theminute, second, and frame of the absolute address.

By using the four bits Q53 through Q56, the time “AHOUR”, which is ahigher concept than “AMIN”, “ASEC”, and “AFRAME”, is recorded.Accordingly, the absolute address, as well as the relative address, isrepresented by hour/minute/second/frame.

The absolute addresses are addresses successively provided from the headof the first track (i.e., the head of the program area) to the lead-outarea.

The sub-Q code of the CD format is represented as discussed above. Inthe sub-Q code, AMIN, ASEC, and AFRAME (and AHOUR) areas are providedfor representing the absolute address, and MIN, SEC, and FRAME (andHOUR) areas are provided for designating the relative address.Additionally, as the address pointer indicating the heads of the trackand the lead-out area, PMIN, PSEC, and PFRAME (and PHOUR) are disposed.These values indicate the address by the minute, second, and frame (andhour), each having eight bits (and hour having four bits) in BCD.

The BCD is a notation representing “0” through “9” in units of fourbits. Thus, according to eight-bit BCD, the values from “00” to “99” canbe represented, namely, the upper four bits represent the tens location,and the lower four bits designate the ones location. According tofour-bit BCD, the values from “0” to “9” can be represented.

In the example shown in FIGS. 30A and 30B, the track number (TNO), thepoint (POINT), and the index (X) are represented by the eight-bit binarycode ranging from “00” to “9F”.

More specifically, the track number (TNO), for example, can berepresented by a range from “0” to “9F (=159)” by taking the values“00000000” through “10011111”, respectively. Accordingly, the number oftracks which can be managed on the format is expanded to 159.

As in the example shown in FIG. 29A, in FIG. 30A, it is determined thatthe track number “00” represents the lead-in area and “AA” (=10101010)designates the lead-out area.

The point (POINT) and the index (X) can also be represented by a rangefrom “0” to “9F” by taking the values “00000000” through “10011111”,respectively. It is thus possible to correspond the point (POINT) to thetrack number (TNO). By using the index (X), one track can be dividedinto 159 portions.

The reason for representing the track number and the index number by“00” through “9F” in binary code is as follows.

As described above, in the known CD format, i.e., in the sub-codeinformation shown in FIG. 29A, a specific definition, such as “A0”,“A2”, “A3”, “B*” or “C*”, is used for the point (POINT) unless POINTindicates the track number. In both the examples shown in FIGS. 29A and30A, “F0” can be used as the value of POINT, which is discussed indetail below.

Accordingly, if “A0” after “9F” is included to represent the tracknumber, “A0”, which is originally meant for a special code, must be usedwhen the point (POINT) represents the track number.

If the point (POINT) uses “A0”, “A2”, “A3”, “B*”, “C*”, and so on, asthe track number in binary code, the definition of “A1” must bedifferentiated between the standard density mode and the high densitymode, which impairs the compatibility. For example, in arecording/reading apparatus, the burden of software and hardware isincreased in order to cope with the different definitions between thestandard density mode and the high density mode.

Thus, it is determined that the track number is expanded only up to “9F”(=159), and “A0” and the subsequent code are not used for the tracknumber. Even in the high density mode, “A0” and the subsequent code areused for defining factors other than the track number.

Accordingly, as the value of the point (POINT), “00” through “9F” areused for the track number, and “A0” and the subsequent code are used forthe special definitions.

According to the allocation of code to the point (POINT), i.e., “00” to“9F” except for the special definitions, “00” through “9F” in binarycode are also allocated to the index (X), which has the same bitallocation on the sub-code format.

Another reason for restricting the track number to “9F” is to enable theuse of the track number “AA” in the standard density mode, i.e., thedefinition of the track number representing the lead-out area, also inthe high density mode.

As discussed above, in the sub-Q data in the lead-in area (i.e., the TOCdata), the value of the point (POINT) determines the content of theinformation of the sub-coding frame. The definitions of the sub-codingframes when the point (POINT) indicates “01” through “9F”, “A0”, “A1”,and “A2” have been discussed.

In this embodiment, information to be recorded in the sub-coding framewhen the value of the point (POINT) indicates “F0” is described below.

FIG. 32 illustrates the content of the sub-coding frame, i.e., MIN, SEC,FRAME, HOUR, PHOUR, PMIN, PSEC, and PFRAME, according to the value ofthe point (POINT) when the ADR is 1, i.e., when the sub-Q data is in thenormal mode.

As discussed above, various types of information indicated by (a) ofFIG. 32 are recorded when the value of the point (POINT) is one of “01”through “9F”, “A0”, “A1”, and “A2”.

When the value of the point (POINT) is “F0”, physical information of amedium is recorded in PMIN, PSEC, PFRAME.

The sub-coding frame shown in FIG. 32 is based on the sub-Q datastructured as shown in FIG. 30A. If it is based on the sub-Q datastructured as shown in FIG. 29A, physical information of a medium canalso be recorded in PMIN, PSEC, and PFRAME when the value of the point(POINT) is “F0”.

The content of the physical information is indicated by (b) of FIG. 32.In PMIN, PSEC, and PFRAME, i.e., in Q57 through Q80, information, suchas the material, the medium type, the linear velocity, and the trackpitch, each having four bits, the moment of inertia, the configuration,and the disc size, each having two bits, are recorded, as indicated by(b) of FIG. 32.

The information of the four-bit disc size is shown in FIG. 33. The value“0000” indicates that the disc size is 120 mm. The value “0001”indicates that the disc size is 80 mm. The other values are reserved.

The information of the two-bit disc configuration is shown in FIG. 34.The value “00” indicates that the disc is circular. The normal circulardisc is a 12- or 8-cm disc. The value “01” indicates that the disc is atriangle. The value “10” indicates that the disc is a quadrilateral. Thevalue “11” indicates that the disc has a configuration other than theabove-described configurations. The other values are reserved

The two-bit moment-of-inertia information is shown in FIG. 35. The value“00” indicates that the moment of inertia is less than 0.01 g·m². Thevalue “01” indicates that the moment of inertia is 0.01 g·m² or greaterbut less than 0.02 g·m². The value “10” indicates that the moment ofinertia is 0.02 g·m² or greater but less than 0.03 g·m². The value “11”indicates that the moment of inertia is 0.03 g·m² or greater.

By referring to the disc configuration and the moment-of-inertiainformation, a disc drive unit is able to determine them. Additionally,various configurations of discs, details of the information, such as thedisc size, the configuration, and the moment of inertia, andmodifications of such information, can be considered. However, thesefactors have been discussed above while referring to the wobbleinformation. An explanation thereof is thus omitted.

The four-bit track pitch information is shown in FIG. 36. When the valueis “0000”, the track pitch is 1.05 μm. When the value is “0001”, thetrack pitch is 1.10 μm. When the value is “0010”, the track pitch is1.15 μm. When the value is “0011”, the track pitch is 1.20 μm. When thevalue is “1000”, the track pitch is 1.50 μm. When the value is “1001”,the track pitch is 1.55 μm. When the value is “1010”, the track pitch is1.60 μm. When the value is “1011”, the track pitch is 1.65 μm. When thevalue is “1100”, the track pitch is 1.70 μm. The other values arereserved.

The track pitch indirectly designates the disc density (standarddensity/high density). That is, “0000” through “0011” indicates that thedisc is a high density disc, while “1000” through “1100” indicates thatthe disc is a standard density.

The four-bit linear velocity information is shown in FIG. 37. When thevalue is “0000”, the linear velocity is 0.84 m/s. When the value is“0001”, the linear velocity is 0.86 m/s. When the value is “0010”, thelinear velocity is 0.88 m/s. When the value is “0011”, the linearvelocity is 0.90 m/s. When the value is “0100”, the linear velocity is0.92 m/s. When the value is “0101”, the linear velocity is 0.94 m/s.When the value is “0110”, the linear velocity is 0.96 m/s. When thevalue is “0111”, the linear velocity is 0.98 m/s. When the value is“1000”, the linear velocity is 1.15 m/s. When the value is “1001”, thelinear velocity is 1.20 m/s. When the value is “1010”, the linearvelocity is 1.25 m/s. When the value is “1011”, the linear velocity is1.30 m/s. When the value is “1100”, the linear velocity is 1.35 m/s.When the value is “1101”, the linear velocity is 1.40 m/s. When thevalue is “1110”, the linear velocity is 1.45 m/s. The value is “1111” isreserved.

The linear velocity also directly designates the disc density (standarddensity/high density). That is, “0000” through “0111” indicates a highdensity disc, while “1000” through “1110” indicates a standard densitydisc.

The four-bit medium type information is shown in FIG. 38. The value“0000” indicates that the medium is a read only medium. The value “0001”indicates that the medium is a DRAW (WORM) medium. The value “0010”indicates that the medium is a rewritable medium. The value “0011” isreserved. The value “0100” indicates that the medium is a hybrid mediumhaving a read only area and a DRAW (WORM) area. The value “0101”indicates that the medium is a hybrid medium having a read only area anda rewritable area. The value “0110” indicates that the medium is ahybrid medium having a DRAW (WORM) area and a read only area. The value“0111” indicates that the medium is a hybrid medium having a rewritablearea and a DRAW (WORM) area. The value “1000” indicates that the mediumis a hybrid medium having a standard-density read only area and a highdensity read only area. The other values are reserved.

The four-bit material information is shown in FIG. 39. When the value is“0000”, embossed pits are formed on the recording layer, i.e., thematerial of the recording layer is a material used for read only discs.When the value is “1000”, the material of the recording layer is cyanineused for DRAW (WORM) media. When the value is “1001”, the material ofthe recording layer is phtalocyanine used for DRAW (WORM) media. Whenthe value is “1010”, the material of the recording layer is an azocompound used for DRAW (WORM) media. When the value is “1011”, thematerial of the recording layer is a phase change material used forrewritable media. The values “0001” through “0111” and “1100” through“1111” are reserved.

As discussed above, the physical information of the medium is recordedin the sub-Q data (TOC) of the lead-in area. This enables a disc driveunit to easily and precisely determine the disc size, the configuration,the moment of inertia, the track pitch, the linear velocity, the mediumtype, and the material of the recording layer.

Instead of the physical information of the recording medium in the sub-Qdata (TOC) of the lead-in area shown in FIGS. 32 through 39, physicalinformation shown in FIGS. 4045 may be employed.

As the sub-Q data indicated by (a) of FIG. 32, the content of the sub-Qdata when ADR is 1, i.e., the content of the sub-Q data in the normalmode, is shown in (a) of FIG. 40. More specifically, the content of thesub-coding frame according to the value of the point (POINT), i.e., thecontent of MIN, SEC, FRAME, HOUR, PHOUR, PMIN, PSEC, and PFRAME, isshown.

The information indicated in (a) of FIG. 40 is similar to that indicatedin (a) of FIG. 32. However, the physical information of a medium to berecorded in PMIN, PSEC, and PFRAME when the value of the point (POINT)is “F0” may be recorded as indicated in (b) of FIG. 40 rather than thatindicated in (b) of FIG. 32.

The sub-Q data indicated in (a) of FIG. 40, as well as that indicated in(a) of FIG. 32, is based on the structure of the sub-Q data shown inFIG. 30A. If it is based on the structure of the sub-Q data shown inFIG. 29A, and the value of the point (POINT) is “F0”, the physicalinformation of the medium indicated in (b) of FIG. 40 can also berecorded in PMIN, PSEC, and PFRAME.

In the physical information designated in (b) of FIG. 40, in the 24 bitsof PMIN, PSEC, and PFRAME, i.e., in Q57 through Q80, a four-bit mediumtype, a four-bit medium version, a four-bit material type, a two-bitlinear velocity, a two-bit track pitch, a three-bit moment of inertia,and a four-bit disc size/configuration are recorded.

The four-bit disc size/configuration is shown in FIG. 41.

When the value is “0000”, the disc size is 120 mm. When the value is“0001”, the disc size is 80 mm. The other values are reserved. Byutilizing the reserved values, the other disc sizes and configurationsmay be recorded.

For example, Q79 and Q80 may be used for the disc size information, andQ77 and Q78 may be used for the disc configuration.

The two-bit disc configuration may be defined as in the informationshown in FIG. 34. More specifically, when the value is “00”, the disc isa regular circular disc. When the value is “01”, the disc is atriangular disc. When the value is “10”, the disc is a rectangular disc.When the value is “11”, the disc has a configuration other than theabove-described configurations.

Alternatively, if the number of combination types of the disc size andthe disc configuration is within 16, they may be defined in the fourbits Q77 through Q80 by using “0000” through “1111”.

As the three-bit moment-of-inertia information recorded in Q74 throughQ76, the definition shown in FIG. 23 may be used.

More specifically, the value “000” indicates that the moment of inertiais less than 0.004 g·m². The value “001” indicates that the moment ofinertia is 0.004 g·m² or greater but less than 0.01 g·m². The value“010” indicates that the moment of inertia is 0.01 g·m² or greater butless than 0.022 g·m². The value “011” indicates that the moment ofinertia is 0.022 g·m² or greater but less than 0.032 g·m². The value“100” indicates that the moment of inertia is 0.032 g·m² or greater butless than 0.037 g·m². The value “101” indicates that the moment ofinertia is 0.037 g·m² or greater. The values “110” and “111” arereserved.

The two-bit track pitch information is shown in FIG. 42. When the valueis “00”, the track pitch is 1.10 μm. The other values are reserved.

The two-bit linear velocity information is shown in FIG. 43. The value“00” indicates that the linear velocity is 0.9 m/s. The other values arereserved.

As the four-bit material type information from Q65 through Q68, thedefinition from Q57 to Q60 shown in FIG. 39 may be used.

The four-bit medium version information is shown in FIG. 44. The value“0000” indicates that the version is 0.9. The value “0001” indicatesthat the version is 1.0. The other values are reserved.

The four-bit medium type information is shown in FIG. 45. The value“0000” indicates that the disc is a high-density (double-density) readonly medium. The value “0001” indicates that the disc is a high-densityDRAW (WORM) medium. The value “0010” indicates that the disc is a highdensity rewritable medium. The other values are reserved.

According to the above-described physical information of a medium in thesub-Q data (TOC) of the lead-in area, the disc drive unit is able toeasily and correctly determine the disc size, the disc configuration,the moment of inertia, the track pitch, the linear velocity, the mediumtype, the material of the recording layer, and the version.

As discussed above, in the multi-session type, such as CD-R, CD-RW,CD-EXTRA, etc., the value of the ADR of the sub-Q data may be “0101”,i.e., mode 5.

In this embodiment, when the ADR in the sub-Q data (TOC) in the lead-inarea is mode 5, the information shown in FIG. 46 is recorded accordingto the value of the point (POINT). The information shown in FIG. 46 isuseful for a hybrid disc having a plurality of areas, each having alead-in area, a program area, and a lead-out area, which are referred toas a “unit area” for a recording/reading operation.

When the value of the point (POINT) is “B0”, the absolute time (absoluteaddress) at which the program area of the subsequent unit area starts isrecorded in MIN, SEC, FRAME, and HOUR. In PHOUR, PMIN, PSEC, and PFRAME,the absolute time (absolute address) at which the lead-out area of thefinal unit area of the disc starts is recorded.

When the value of the point (POINT) is “C0”, special information 1 ofthe above-described wobble information is recorded in MIN, SEC, FRAME,and HOUR. In PHOUR, PMIN, PSEC, and PFRAME, the absolute time (absoluteaddress) at which the lead-in area of the first unit area of the discstarts is recorded.

When the value of the point (POINT) is “C1”, the above-described specialinformation 1 is copied in MIN, SEC, FRAME, and HOUR. PHOUR, PMIN, PSEC,and PFRAME are reserved.

When the value of the point (POINT) is “CF”, the absolute time (absoluteaddress) at which the lead-out area of the current unit area ends isrecorded in MIN, SEC, FRAME, and HOUR. In PHOUR, PMIN, PSEC, and PFRAME,the absolute time (absolute area) at which the lead-in area of thesubsequent unit area starts is recorded.

When the value of the point (POINT) is “CF” in the final unit area, theinformation in PHOUR, PMIN, PSEC, and PFRAME is set to zero since thereis no subsequent unit area. Alternatively, the sub-code frame in whichthe point (POINT) is “CF” is not provided.

As described above, in this embodiment, by referring to the informationof the sub-Q data of a hybrid disc, in particular, the “absolute time atwhich the lead-in area of the subsequent unit area starts” when thevalue of the point (POINT) is “CF”, the position of the lead-in area ofthe subsequent unit area can be precisely determined.

For example, FIG. 47A schematically illustrates a disc having two unitareas #1 and #2, and FIG. 47B schematically illustrates a disc havingthree unit areas #1, #2, and #3. According to the sub-Q data read fromthe lead-in area of a unit area, the position of the lead-in area of thesubsequent unit area can be identified, as shown in FIGS. 41A and 41B.This enables a disc drive unit to sequentially access the lead-in areasof the individual unit areas, as indicated by the one-dot-chain arrows,thereby easily reading the TOC data of each unit area.

In the sub-code of the lead-in area of each unit area, the absolute timeat which the current lead-out area of the unit area ends is recorded.Thus, any gap between the lead-out area of the current unit area and thelead-in area of the subsequent unit area can be correctly identified.

5. Configuration of Disc Drive Unit

A description is now given of a disc drive unit for performing arecording/reading operation in accordance with the above-describedvarious types of discs.

FIG. 48 is a block diagram illustrating the configuration of a discdrive unit 70. In FIG. 48, a disc 90 is a CD format disc, such as aCD-R, a CD-RW, a CD-DA, or a CD-ROM. Various types of discs, asdiscussed with reference to FIGS. 1A through 5B, may be loaded in thedisc drive unit 70.

The disc 90 is loaded on a turntable 7, and is rotated at a CLV or a CAVby a spindle motor 6 during a recording/reading operation. Then, pitdata is read from the disc 90 by an optical pick-up 1. As the pit data,when the disc 90 is a CD-RW, pits formed by a phase change are read.When the disc 90 is a CD-R, pits formed by a change in an organicpigment (index of reflection) are read. When the disc 90 is a CD-DA or aCD-ROM, embossed pits are read.

The optical pick-up 1 contains a laser diode 4, which serves as a laserlight source, a photodetector 5 for detecting reflected light, anobjective lens 2, which serves as an output terminal of laser light, andan optical system (not shown) for applying the laser light to therecording surface of the disc via the objective lens 2 and also forguiding the light reflected by the disc to the photodetector 5. Amonitoring detector 22 for receiving part of the light output from thelaser diode 4 is also provided for the optical pick-up 1.

The objective lens 2 is held by a two-axes mechanism 3 movably in thetracking direction and the focusing direction. The entire opticalpick-up 1 is movable along the radius of a disc by a sled mechanism 8.The laser diode 4 of the optical pick-up 1 is driven by a drive signal(drive current) from a laser driver 18.

The reflected light information from the disc 90 is detected by thephotodetector 5 and is converted into an electrical signal based on theamount of received light. The electrical signal is then supplied to anRF amplifier 9.

Generally, the RF amplifier 9 is provided with an AGC circuit. This isbecause the amount of light reflected by a CD-RW considerably changesaccording to whether data is recorded on the disc 90 or whether data iscurrently recorded on the disc 90 in comparison with a CD-ROM, and also,the index of reflection of a CD-RW is very different from that of aCD-ROM or a CD-R.

The RF amplifier 9 is also provided with a current-to-voltage conversioncircuit, a matrix-computing/amplifying circuit, etc. to cope with theoutput currents from a plurality of light receiving devices, which formthe photodetector 5, thereby generating signals by performing matrixcomputation. For example, an RF signal (read data), a focus error signalFE and a tracking error signal TE for performing servo control aregenerated.

The read RF signal output from the RF amplifier 9 is supplied to abinarizing circuit 11, while the focus error signal FE and the trackingerror signal TE are supplied to a servo processor 14.

As described above, a groove for guiding a recording track is pre-formedon the disc 90, such as a CD-R or a CD-RW. The groove wobbles (meanders)according to a signal formed by performing frequency modulation on timeinformation indicating the absolute address on the disc. Accordingly,during the recording/reading operation, by referring to the grooveinformation, tracking servo can be performed, and the absolute addressand various physical information can be obtained. The RF amplifier 9extracts wobble information WOB by performing matrix computation, andsupplies it to a groove decoder 23.

The groove decoder 23 demodulates the received wobble information WOB soas to extract the absolute address and supplies it to a systemcontroller 10.

The groove information is also input into a phase locked loop (PLL)circuit so as to obtain rotational velocity information of the spindlemotor 6. By comparing the rotational velocity information with thereference velocity information, a spindle error signal SPE is generatedand output.

Recordable discs, such as CD-R and CD-RW, include two types of disc,such as a standard density disc and a high density disc. The groovedecoder 23 switches the decode system according to the density typeinformation output from the system controller 10. More specifically, thegroove decoder 23 switches the matching pattern of a framesynchronization.

The read RF signal obtained in the RF amplifier 9 is binarized in thebinarizing circuit 11 so as to be converted to an eight-to-fourteen(EFM) signal. The EFM signal is supplied to an encoder/decoder 12.

The encoder/decoder 12 has both functions, such as a decoder functionrequired for reading data, and an encoder function required forrecording data. When data is read, the encoder/decoder 12 performs EFMdemodulation, CIRC error correcting, deinterleaving, CD-ROM decoding,etc., thereby outputting CD-ROM formatted data.

The encoder/decoder 12 also extracts the sub-code from the data readfrom the disc 90 and supplies it to the system controller 10 as the TOCand address information as sub-code (Q data).

Additionally, the encoder/decoder 12 generates a reading clock insynchronization with the EFM signal by performing PLL processing, andexecutes the above-described decoding operation based on the readingclock. In this case, the encoder/decoder 12 extracts the rotationalvelocity information of the spindle motor 6 from the reading clock, andcompares it with the reference velocity information, thereby generatingthe spindle error signal SPE and outputting it.

The encoder/decoder 12 is able to switch the processing method accordingto whether the disc (or unit area) to be read or recorded is a standarddensity disc or a high density disc.

During the reading operation, the encoder/decoder 12 stores theabove-described decoded data in a buffer memory 20. When outputting theread data from the disc drive unit 70, the data stored in the buffermemory 20 is read and output.

An interface 13 is connected to an external host computer 80, andrecording data, read data, and various commands are sent and receivedtherebetween. As the interface 13, a small computer system interface(SCSI) or an AT attachment packet interface (ATAPI) is used. Whenreading data, the read data decoded and stored in the buffer memory 20is transferred to the host computer 80 via the interface 13.

A read command, a write command, and other commands from the hostcomputer 80 are supplied to the system controller 10 via the interface13.

When recording data, recording data (such as audio data or CD-ROM data)is transferred from the host computer 80, and is then stored in thebuffer memory 20 via the Interface 13.

In this case, the encoder/decoder 12 performs encoding processing on theCD-ROM format data (when the supplied data is CD-ROM data), such as CIRCencoding, interleaving, sub-code addition, and EFM modulation, therebyforming CD-format data.

The EFM signal obtained by the encoding processing of theencoder/decoder 12 is supplied to a write strategy unit 21 in which thewaveform of the EFM signal is shaped. Then, the EFM signal is suppliedto the laser driver 18 as a laser drive pulse (write data WDATA).

The write strategy unit 21 provides compensation for recording data,that is, finely adjusting the optimal recording power and shaping thelaser drive pulse waveform, according to the characteristics of therecording layer, the spot configuration of laser light, and therecording linear velocity.

The laser driver 18 applies the laser drive pulse supplied as the writedata WDATA to the laser diode 4, thereby driving the emission of laserlight. Accordingly, pits (phase change pits or pigment change pits) inaccordance with the EFM signal are formed on the disc 90.

An auto power control (APC) circuit 19 controls the laser output to bemaintained at a constant value without being influenced by thetemperature while monitoring the laser output power from the monitoringdetector 22. Given by the target laser output value from the systemcontroller 10, the APC circuit 19 controls the laser driver 18 so thatthe target value is reached.

The servo processor 14 generates various servo drive signals, such asfocus, tracking, sled, and spindle signals, from the focus error signalFE and the tracking error signal TE output from the RF amplifier 9 andthe spindle error signal SPE output from the encoder/decoder 12 or thegroove decoder 23.

More specifically, the servo processor 14 generates a focus drive signalFD and a tracking drive signal TD based on the focus error signal FE andthe tracking error signal TE, respectively, and supplies them to atwo-axes driver 16. The two-axes driver 16 then drives a focus coil anda tracking coil of the two-axes mechanism 3 of the optical pick-up 1.Accordingly, a tracking servo loop and a focus servo loop are formed bythe optical pick-up 1, the RF amplifier 9, the servo processor 14, thetwo-axes driver 16, and the two-axes mechanism 3.

In response to a track jump command from the system controller 10, thetracking servo loop can be turned off, and a jump drive signal is outputto the two-axes driver 16. The two-axes driver 16 then performs thetrack jump operation.

The servo processor 14 also generates a spindle drive signal based onthe spindle error signal SPE and supplies it to a spindle motor driver17. In response to the spindle drive signal, the spindle motor driver 17applies, for example, a three-phase drive signal, to the spindle motor6, which is then rotated at a CLV or CAV.

The servo processor 14 also generates a spindle drive signal based on aspindle kick/brake control signal from the system controller 10, andcauses the spindle motor driver 17 to start, stop, accelerate, anddecelerate the spindle motor 6.

Additionally, the servo processor 14 generates a sled error signalobtained as a low frequency component of the tracking error signal TE,and a sled drive signal based on the access control by the systemcontroller 10, and supplies them to a sled driver 15. In response to thesled drive signal, the sled driver 15 drives the sled mechanism 8. Thesled mechanism 8 is provided with a main shaft, a sled motor, and atransfer gear (none of which is shown), for holding the optical pick-up1. By driving the sled mechanism 8 by the sled driver 15 according tothe sled drive signal, the optical pick-up 1 slides on the disc 90.

The above-described various operations by the servo system and therecording/reading system are controlled by the system controller 10,which is formed of a microcomputer.

The system controller 10 executes the above-described operations inresponse to commands from the host computer 80. For example, uponreceiving a read command, which instructs the system controller 10 totransfer certain data recorded on the disc 90, from the host computer80, the system controller 10 first controls the seek operation to thedesignated address. That is, the system controller 10 instructs theservo processor 14 to cause the optical pick-up 1 to access the addressdesignated by the seek command.

Thereafter, the system controller 10 performs the operation required fortransferring the read data to the host computer 80. That is, the data isread from the disc 90, decoded, and temporarily stored. Then, therequested data is transferred to the host computer 80.

In contrast, in response to a write command from the host computer 80,the system controller 10 first moves the optical pick-up 1 to theaddress at which data is to be written. Then, the encoder/decoder 12performs encoding processing, as discussed above, on the datatransferred from the host computer 80, so as to be converted into an EFMsignal.

Subsequently, the write data WDATA output from the write strategy unit21 is supplied to the laser driver 18, thereby recording the requesteddata on the disc 90.

In the example shown in FIG. 48, the disc drive unit 70 is connected tothe host computer 80. However, the disc drive unit 70, such as an audioCD player or CD recorder, which forms the recording/reading apparatus ofthe present invention, does not have to be connected to the hostcomputer 80. In this case, the configuration of the interface 13 isdifferent from that shown in FIG. 48, for example, the interface 13 maybe provided with an operation unit and a display unit. That is, data maybe recorded and read by the user's operation, and a terminal forinputting and outputting audio data may be formed. On the display unit,the currently recorded or read track number and the time (absoluteaddress or relative address) may be displayed.

Various other configurations of the disc drive unit 70 are considered,for example, a record only apparatus or a read only apparatus may beprovided.

6. Examples of Processing of Disc Drive Unit

Various processing examples of the disc drive unit 70 are discussedbelow.

FIG. 49 is a flow chart of an example of the processing executed by thedisc drive unit 70 when the disc 90 is inserted. It should be noted thatthe TOC formed by the sub-Q data is recorded in the lead-in area of thedisc 90. If a virgin disc (unrecorded disc) is loaded as a CD-R or aCD-RW, the processing shown in FIG. 50 is performed rather than theprocessing shown in FIG. 49 since the TOC is not recorded on such adisc.

The processing indicated by the flow charts of FIGS. 49 through 52 isexecuted by the system controller 10.

In FIG. 49, when the disc 90 is loaded, in step F101, the systemcontroller 10 performs the start-up operation and reads the TOC. Morespecifically, the system controller 10 starts the spindle motor 6,maintains the servo mechanism at a predetermined rotational velocity,starts laser emission, activates and maintains focus servo, andmaintains tracking servo so that data can now be read from the disc 90,and then reads the TOC information.

Then, in step F102, the system controller 10 reads the physicalinformation of the disc 90 from the TOC information, thereby determiningthe physical characteristics of the disc 90. This operation can beperformed by checking the information shown in FIGS. 32 through 39.

It is then determined in step F103 whether the disc 90 is a hybrid disc.This can be determined by the medium type shown in FIG. 38. If theoutcome of step F103 is no, the process proceeds to step F104 in whichthe recording/reading system is set according to the physicalinformation of the type of the disc 90. The setting operation isdiscussed in detail below with reference to FIG. 51.

A recording/reading operation is now ready to be performed on the disc90. In step F105, the system controller 10 waits for a command from thehost computer 80, and executes a reading or recording operation inresponse to a read command or a write command, respectively.

If it is found in step F103 that the disc 90 is a hybrid disc, avariable n is set to 1 in step F106, and the loop processing from stepsF107 to F112 is performed.

More specifically, in step F107, the physical information read in stepF102 is stored as physical information of a unit area #(n), namely,physical information of, for example, the unit area #1 shown in FIG. 47Aor 47B.

Subsequently, in step F108, the variable n is incremented. Then, in stepF109, the start address of the lead-in area of the subsequent unit areais determined.

As discussed with reference to FIG. 46, in the sub-code frame in whichthe ADR is mode 5 and the point (POINT) is CF, the start address of thelead-in area of the subsequent unit area is recorded. Thus, in stepF109, this information is checked.

If the start address of the lead-in area of the subsequent unit area isrecorded in the above-described sub-code frame, the presence of thesubsequent unit area can be automatically confirmed, and thus, theprocess proceeds from F110 to F111. In step F111, the system controller10 controls the servo processor 14 to access the recorded start addressof the lead-in area.

When the optical pick-up 1 reaches the lead-in area of the subsequentunit area, in step F112, the system controller 10 reads the TOCinformation. The TOC information contains the physical information shownin FIGS. 32 through 39.

The process then returns to step F107 in which the read physicalinformation is stored as the physical information of the unit area #(n).In this case, the physical information of the unit area #2 is stored.

The above-described processing is repeated until the physicalinformation of the final unit area is incorporated. That is, when thestart address of the lead-in area of the subsequent unit area is readfrom the sub-code frame in which the ADR is mode 5 and the point (POINT)is CF in step F109, the address value is zero, or such a sub-code frameitself does not exist. In this case, it can be determined that thecurrent unit area is the final unit area.

Accordingly, it is determined in step F110 that there is no subsequentunit area, and the process proceeds to step F113.

That is, the system controller 10 waits for a command from the hostcomputer 80 after storing the physical information of all the unitareas, and performs a reading or recording operation in response to theread command or the write command, respectively. Then, before performingthe recording or reading operation, the system controller 10 sets therecording/reading system based on the physical characteristics of theunit area from or into which data is read or recorded.

In contrast, when a virgin disc without TOC information is loaded as aCD-R or a CD-RW, the system controller 10 performs the processing shownin FIG. 50.

In step F201, the system controller 10 starts the spindle motor 6,begins the emission of laser light, and then roughly maintains thespindle servo, activates and maintains the focus servo, and maintainstracking servo while positioning the optical pick-up 1 on the innerperiphery of the disc 90. The reading operation can now be performed onthe disc 90.

Subsequently, in F202, wobble information is read from the groove on thedisc 90. The physical information of the disc 90 is read from the wobbleinformation so as to determine the physical characteristics of the disc90. This operation can be performed by checking the information shown inFIGS. 13 through 23.

Then, in step F203, the recording/reading system is set according to thephysical information of the disc 90. The setting information isdiscussed in detail below with reference to FIG. 51.

Thus, the recording operation can be performed on the disc 90. In stepF204, the system controller 10 waits for a command from the hostcomputer 80, and executes the recording operation according to the writecommand.

As discussed above, in this embodiment, when the disc 90 is loaded, thephysical characteristics of the disc 90 are determined from the sub-Qdata (TOC) or the wobble information, and various settings are madeaccording to the determined physical characteristics.

The setting operation executed in step F104 of FIG. 49 or F203 of FIG.50 is performed by, for example, the processing shown in FIG. 51.

In step F301, the disc configuration is first checked. That is, in thecase of the wobble information, the configuration information describedwith reference to FIGS. 17 through 21B, and if necessary, themoment-of-inertia information shown in FIG. 22 is checked. In the caseof the sub-Q data, the configuration information shown in FIG. 34 andthe moment-of-inertial information shown in FIG. 35 are checked.

The system controller 10 then determines whether the configuration ofthe disc 90 is suitable to perform the reading or recording operation bythe disc drive unit 70. This can be determined by the design of the discdrive unit 70, such as the structure of the unit itself, and thevariable range of various parameters, such as the servo coefficient.

If it is found in step F301 that the configuration of the disc 90 is notsuitable, the process proceeds to F302 in which an error message isoutput. Then, in step F303, the disc 90 is ejected, and the processingis ended.

The error message is sent to the host computer 80, and may be displayedon the monitor display of the host computer 80, or may be displayed on adisplay unit of the disc drive unit 70. An audio warning may be issued.

If it is found in step F301 that the configuration of the disc 90 issuitable, the process proceeds to step F304 in which the operation modeis set according to the disc density. In step F304, the disc density canbe determined by the disc density information shown in FIG. 15 whenusing the wobble information. Or, when using the sub-Q data, the mediumtype shown in FIG. 38, the track pitch shown in FIG. 36, or the linearvelocity shown in FIG. 37 can be checked.

Then, the processing mode in the encoder/decoder 12 or the processingmode in the groove decoder 23 is switched according to whether the discdensity is high density or standard density.

According to the disc density, the RF gain and the equalizingcharacteristics of the RF amplifier 9, various servo gains, such asfocusing and tracking gains, and the setting of the computationcoefficients used for the seeking operation, which is required to copewith a difference in the track pitch, are also switched.

Thereafter, in step F305, the spindle servo gain is set according to thevalue of the moment of inertia.

This is explained in detail below with reference to FIGS. 53A and 53B.

FIG. 53A is a Bode diagram of a servo open loop when a spindle servogain suitable for a loaded disc having a large moment of inertia is set.According to the relationship between the gain and the phase, as shownin FIG. 53A, a sufficient phase margin and gain margin can be obtained.

FIG. 53B is a Bode diagram of a servo open loop when a spindle servogain which is not suitable for a loaded disc having a small moment ofinertia is set.

In this case, according to the gain and the phase, as shown in FIG. 53B,a sufficient phase margin and gain margin cannot be obtained, therebyimpairing the stability of the system.

If the servo gain is reduced from the value shown in FIG. 53B to thesuitable value shown in FIG. 53A, a sufficient phase margin and gainmargin can be achieved.

That is, there is a suitable value for the spindle servo gain accordingto the moment of inertia of a disc. Accordingly, in the processing ofstep F305, the spindle servo gain is set to an appropriate value bychecking the moment of inertia. Thus, the spindle servo system can bestably operated with high precision. In particular, since highly preciserotation of the spindle is demanded in performing the recordingoperation, this processing is effective.

In step F306, the moving range of the optical pick-up 1 is set based onthe disc configuration.

As described with reference to FIGS. 18A through 20C, the access rangeAC varies according to the disc configuration. Accordingly, based on thedisc configuration (and maybe the above-described dimensions), it isdetermined where the optical pick-up 1 can access on the outer peripheryof the disc 90, thereby setting the sled moving range of the opticalpick-up 1. It is thus possible to prevent the erroneous operation of theoptical pick-up 1, i.e., the application of laser light to a portion ofthe disc 90 without a recording track.

Step F307 is performed only when the disc 90 is a CD-R or a CD-RW. Basedon the material data, the processing to be executed by the writestrategy unit 21 is set. The material data, i.e., the material of therecording layer, can be checked by the material data shown in FIG. 14contained in the wobble information, and by the material type shown inFIG. 39 contained in the sub-Q data.

In the write strategy unit 21, as stated above, the pulse waveform isshaped as the laser drive pulse.

In the case of a CD-R on which data is recorded by a pigment change,laser drive pulses, such as those indicated by (b) of FIG. 54, aregenerated according to the lengths of pits/lands to be recorded, such asthose indicated by (a) of FIG. 54, thereby driving the emission of laserlight. The level PWr of the laser drive pulses indicates the laserrecording power.

In a CD-R, pulses indicated by (b) and (c) of FIG. 54 may be combined,thereby synthesizing step-like laser drive pulses, such as thoseindicated by (d) of FIG. 54. According to the step-like laser pulses,the laser power is increased to PWod in part of the pulse zone in whichpits are generated, and such part is referred to as an “over drivepulse”. By applying the over drive pulses, the laser level can be moreprecisely controlled within the pulse period.

In the case of a CD-RW for recording data by a phase change technique,as indicated by (e) of FIG. 54, laser drive pulses (pulse train) aregenerated in which the laser power is switched between the recordingpower PWr and cooling power PWc in the pit forming zone, thereby drivinglaser light. During the land period, the laser power is set to erasingpower PWe.

By finely adjusting the laser drive pulses for a CD-R and a CD-RWaccording to the material of the recording layer, the recordingprecision can be enhanced.

More specifically, in each pulse waveform shown in FIG. 54, according tothe material of the recording layer, the timing adjustment (i.e.,laser-pulse width adjustment) is performed by controlling the risingportions and the falling portions indicated by , and the leveladjustment (i.e., laser power adjustment) is performed by controllingthe pulse level indicated by ◯.

The reason for controlling the pulse waveform according to the pulsewidth and the laser power is as follows.

For example, in the case of a DRAW (WORM) disc, such as a CD-R, in orderto record a longer pit, the ratio of the recording laser power to thereading laser power should be increased. Accordingly, a large amount ofheat is accumulated so as to increase a region in which a chemicalreaction is caused. As a result, the pit to be actually recorded becomeslonger than a prescribed length. This phenomenon is more noticeable whenthe thermal sensitivity or the heat conduction of the recording layer ofa disc is higher.

The length of the pit to be recorded is also influenced by the length ofthe preceding land. That is, as the land located immediately before thepit to be recorded becomes shorter, the heat accumulated in thepreceding pit becomes less dissipated, thereby encouraging heatinterference from the preceding pit.

For example, among some pits to be recorded, even if the lengths of thepits are the same, and the time for applying laser and power are thesame, a pit adjacent to a shorter land results in a longer pit.

Since the heat accumulation and dissipation varies according to thematerial of the recording layer, the pulse width, the pulseconfiguration (laser emission pattern), and the pulse level (laserlevel) are adjusted according to the material, thereby contributing tothe formation of a high-precision pit string.

As discussed above, according to the physical characteristics of thedisc 90, the setting operation shown in FIG. 51 is performed, therebyimproving the recording/reading performance.

If it is found in step F103 of FIG. 49 that the disc 90 is a hybriddisc, the setting operation shown in FIG. 51 is performed in step F113in a unit area into and from which data is recorded or read.

The physical-characteristic determining operation shown in FIG. 49 or 50and the setting operation shown in FIG. 51 may be performed not onlywhen a disc is inserted, but also when power is turned on while a discis loaded in the disc drive unit 70, or when a command is generated bythe host computer 80.

TOC is not initially recorded on a CD-R or a CD-RW, and the disc driveunit 70 writes TOC information according to the data recording operationon the disc. The TOC writing operation is shown in FIG. 52.

FIG. 52 is a flow chart illustrating processing after data is recordedin a program area of the disc 90, which serves as a CD-R or a CD-RW.Steps F401 and F402 indicate the recording operation in response to acommand from the host computer 80.

Upon completion of the recording of user data, in step F403, the systemcontroller 10 generates TOC data according to the content of therecorded data.

That is, the system controller 10 generates information, such as theaddress of each track, from the values stored in the PMA, and alsogenerates physical information, such as the one shown in FIGS. 32through 39. In this case, the physical information is determined fromthe wobble information.

More specifically, the information indicated in (b) of FIG. 32 isgenerated from the physical information read from the wobbleinformation. The value of the material information indicated in (b) ofFIG. 32 is generated based on the material data shown in FIG. 14. Thevalue of the medium type (in this case, whether the disc is a CD-R orCD-RW, and the density of the disc) indicated in (b) of FIG. 32 isgenerated based on the disc density shown in FIG. 15, the physicalstructure shown in FIG. 16, and the disc type of special information 1shown in FIG. 13.

The linear velocity and the track pitch indicated in (b) of FIG. 32 canbe generated based on the disc density shown in FIG. 15, specialinformation 1 and 4 shown in FIG. 13, and the setting determined whenuser data is recorded. The moment of inertia represented in (b) of FIG.32 is generated based on the moment of inertia shown in FIG. 22. Theconfiguration designated in (b) of FIG. 32 is generated based on thedisc configuration shown in FIG. 17. The disc size indicated in (b) ofFIG. 32 is generated based on the disc configuration shown in FIG. 17and the moment of inertia shown in FIG. 22.

It is not essential, however, that the information indicated in (b) ofFIG. 32 be generated as discussed above.

Then, in step F404, the sub-code frame having the generated TOCinformation is recorded in the lead-in area.

Accordingly, in this embodiment, concerning a CD-R or a CD-RW withoutTOC information, the physical characteristics (physical information) ofsuch a disc can be determined by wobble information. When recording theTOC information later, the physical characteristics determined from thewobble information are recorded in the disc as the TOC information. Thismakes it possible to determine the physical characteristics of the discfrom the TOC, as well as from the wobble information.

A disc drive unit provided with a recording function is designed todecode wobble information. However, some read-only disc drive units arenot provided with a decoding function for wobble information. Thus, bytransferring the physical information of the disc obtained from thewobble information into TOC data, such read-only disc drive units areable to determine the physical information of the disc, andcorrespondingly perform the setting.

7. Examples of DVD-format Discs

In the foregoing embodiment, the present invention has been discussed inthe context of a CD-R and a CD-RW. The present invention is alsoapplicable to other types of discs, and the physical characteristics,such as the moment of inertia and the disc configuration, of the otherdiscs may also be recorded on them. In this case, advantages similar tothose exhibited by the foregoing embodiment can be obtained inperforming a recording or reading operation by a recording apparatus ora reading apparatus.

As an example of the other types of discs, DVD-format discs arediscussed below. As recordable DVD-format discs, a DVD-RW, a DVD-R, aDVD-RAM, and a DVD+RW have been developed, which are described below.

Although a detailed configuration of a disc drive unit(recording/reading apparatus) compatible with such DVD-format discs isslightly different from that of the disc drive unit 70 compatible withCD-format discs shown in FIG. 48 due to differences in the data format,the modulation/demodulation method, the optical characteristics, and soon, the basic configuration of a DVD drive unit is similar to that of aCD drive unit. Thus, an explanation thereof is omitted. As in theoperations described with reference to FIGS. 49 through 54, a disc driveunit compatible with DVD discs, which is discussed below, is able todetermine the physical characteristics of a loaded disc, provide varioussettings according to the physical characteristics, and perform therecording and reading operation correspondingly.

The recording of the physical characteristics of a DVD disc therein isdiscussed below.

7-1 DVD-RW, DVD-R

In a DVD-RW, which is a rewritable disc using a phase-change recordingtechnique, and a DVD-R, which is a DRAW (WORM) disc using anorganic-pigment change technique, a wobbling groove is formed as apre-format on the disc, and a pre-pit is formed on a land locatedbetween grooves (hereinafter referred to as a “land pre-pit”).

The wobbling groove is used for controlling the rotation of the disc andfor generating the recording master clock. The land pre-pit is used fordetermining the accurate recording position of each bit and forobtaining various items of information concerning the disc, such as thepre-address. Thus, the physical characteristic information of the discis recorded in the land pre-pit.

FIG. 55 illustrates the layout of a disc, which serves as a DVD-RW or aDVD-R.

The lead-in area on the inner periphery of the disc is disposed in arange from 45.2 to 48 mm from the center of the disc. The lead-out areais formed at a position away from 116 mm from the center of the disc.The area between the lead-in area and the lead-out area serves as aprogram area in which real data is recorded.

In the information area including the lead-in area, the program area,and the lead-out area, the groove (guide groove), which forms a datatrack, is formed in a wobbling (meandering) shape. Additionally, a landpre-pit LPP is formed, as shown in FIG. 56, at a predetermined positionof a land L between wobbling grooves G, G.

The wobbling groove G information and the land pre-pit LPP informationare obtained-by a so-called push-pull signal representing the lightreflected by the disc detected by an optical pick-up.

The structure of the pre-formatted data recorded as the land pre-pit LPPis as follows.

FIG. 57A illustrates a pre-pit frame, which is a minimum unit of thepre-formatted data as the land pre-pit LPP. The pre-pit frame has twelvebits consisting of a four-bit relative address and eight-bit user data.Then, 16 pre-pit frames (PF0 through PF15) form one pre-pit block. Thefour-bit relative addresses of the individual pre-pit frames indicatethe addresses of the corresponding pre-pit frames (PF0 through PF15).

The pre-pit block is formed of part A consisting of the six pre-pitframes PF0 through PF5 and part B consisting of the ten pre-pit framesPF6 through PF15.

Since one pre-pit frame has eight-bit user data, part A has 48-bit (sixbytes) user data. Among the six-byte user data, as shown in FIG. 57B,three bytes are used as an ECC block address, and three bytes are usedas parity A for part A.

Part B, which consists of the ten pre-pit frames PF6 through PF15, has80-bit (10-byte) user data. The 10-byte user data has, as shown in FIG.57C, a one-byte field ID, six-byte disc information, and three-byteparity B for part B.

The six-byte disc information varies, as shown in FIG. 58, according tothe field ID. In the pre-bit block in which the field ID is ID0, threebytes of the six-byte disc information of part B are used for recordingthe same value of the ECC block address of part A. The pre-pit block inwhich the field ID is ID0 is formed on the entire area of the disc.

The pre-pit block in which the field ID is one of ID1 through ID5 isformed in the lead-in area. In the pre-pit block in which the field IDis ID1, the application code or physical data is recorded as thesix-byte disc information. In the pre-pit block in which the field ID isID2, the OPC suggested code or write strategy code (WS1) is recorded asthe six-byte disc information. In the pre-pit block in which the fieldID is ID3, the manufacturer ID (MID1) is recorded as the discinformation. In the pre-pit block in which the field ID is ID4, themanufacturer ID (MID2) is recorded as the disc information. In thepre-pit block in which the field ID is ID5, write strategy code (WS2) isrecorded as the six-byte disc information.

Details of the structure of the pre-pit block in which the field ID isID1 are shown in FIG. 59. In this case, the six-byte disc information ofthe user data of PF7 through PF12 of the pre-pit frames is formed ofone-byte application code, one-byte disc physical data, a three-bytelast address of the data recordable area, one-byte partversion/extension code.

The contents of the one-byte (eight-bit) disc physical code are definedas shown in FIG. 60A.

Among the eight bits b0 through b7, b7 indicates track pitchinformation. When bit b7 is “0”, the track pitch is 0.80 μm. When bit b7is “1”, the track pitch is 0.74 μm. Bit b6 represents the referencevelocity. The value “0” indicates that the reference velocity is 3.84m/s, while the value “1” indicates that the reference velocity is 3.49m/s. Bit b5 designates the disc size. The value “0” indicates that thedisc size is 12 cm, while the value “1” indicates that the disc size is8 cm. Bit 4 represents the index of reflection. The value “0” indicatesthat the index of reflection ranges from 45 to 85%, while the value “1”indicates that the index of reflection ranges from 18 to 30%.

The medium type is recorded in bit 2 and bit 1. When bit b2 is “1”, themedium type is a phase change medium. When bit 2 is “0”, the medium typeis another type. When bit 1 is “0”, the medium type is a recordabletype. When bit 1 is “1”, the medium type is a rewritable type.

The moment of inertia is recorded in bit b3 and bit b0. When the valuesof bit 3 and bit 0 are represented by J1 and J2, respectively, themoment of inertia can be defined by the two bits J1 and J2, as shown inFIG. 60B.

When the values of J1 and J2 are “00”, the moment of inertia is lessthan 0.01 g·m². When the values of J1 and J2 are “01”, the moment ofinertia is 0.01 g·m² or greater but less than 0.02 g·m². When the valuesof J1 and J2 are “10”, the moment of inertia is 0.02 g·m² or greater butless than 0.03 g·m². When the values of J1 and J2 are “11”, the momentof inertia is 0.03 g·m² or greater.

In the case of a DVD-RW and a DVD-R, as described above, the physicalinformation of a recording medium is recorded in the lead-in area as thepre-bit block of the land pre-bit LPP. This enables a disc drive unit toaccurately and easily determine the disc size, the moment of inertia,the track pitch, the linear velocity, the medium type, etc. Accordingly,the disc drive unit is able to perform suitable settings according tothe physical characteristics of the disc, thereby performing a suitablerecording/reading operation correspondingly.

7-2 DVD-RAM

In a DVD-RAM, which is a DVD-format rewritable disc using a phase-changerecording technique, high density recording is implemented by employinga land/groove recording method. In the DVD-RAM, the lead-in areaincludes a portion in which control information is recorded as embossedpits, and an information rewritable portion. The physical characteristicinformation of a disc can be recorded in the embossed pit area of thelead-in area.

FIG. 61 illustrates the layout of a DVD-RAM. The lead-in area is formed,as shown in FIG. 61, from 45.2 mm from the center of the disc. The areafrom 45.2 to 48.0 mm is an embossed pit area in which controlinformation is recorded. The lead-in area further extends to therewritable area in which data is recorded. The lead-out area is formedfrom 115.78 to 117.2 mm. The area between the lead-in area and thelead-out area is used as a program area in which real data is recorded.

The detailed configuration of the lead-in area is shown in FIG. 62.

The lead-in area is largely formed of an embossed data area, a mirrorarea, and a rewritable area. In the embossed data area, an initial zone,a one-block (ECC block) reference code zone, a 31-block buffer zone, a192-block control data zone, and a 32-block buffer zone are sequentiallydisposed.

Subsequently, in the rewritable area after a mirror area (connectionzone), a 32-block guard track zone, a 64-block disc test zone, a112-block drive test zone, a 32-block guard track zone, an 8-block discidentification zone, an 8-block defect management area (DMA)1, and an8-block DMA2 are sequentially disposed.

The configuration of each of the 192 blocks of the control data zone inthe embossed data area is shown in FIG. 63.

One block is formed of 16 sectors from sector 0 to sector 15. One sectorhas 2048 bytes. In sector 0, physical format information is recorded. Insector 1, disc manufacturing information is recorded. 192 blocksconfigured as described above are recorded in the control data zone.

The contents of the physical format information (2048 bytes) recorded insector 0 are partially shown in FIG. 64. In the head byte at byteposition 0 of the 2048-byte sector, the medium type and the part versionis recorded.

In the subsequent byte at byte position 1, the moment of inertia, thedisc size, and the maximum transfer rate are recorded. This informationhas, for example, eight bits of bit 0 to bit 7, as shown in FIG. 65, inwhich the maximum transfer rate is recorded in four bits from b0 to b3,the disc size is recorded in two bits from b4 and b5, and the moment ofinertia is recorded in two bits b6 and b7. Concerning the two bits b4and b5 representing the disc size, the value “00” may represent a 12-cmdisc, while the value “01” may indicate an 8-cm disc, and the othervalues may be reserved. Alternatively, by using the two bits b4 and b5,a combination of the disc size and the disc configuration may beindicated rather than only the disc size. The two bits b7 and b6designating the moment of inertia may be represented by J1 and J2,respectively, and the moment of inertia may be defined as shown in FIG.60B.

In FIG. 64, at byte position 2 (one byte), the disc structure isrecorded as a predetermined definition. At byte position 3 (one byte),the recording density is recorded as a predetermined definition. At byteposition 32 (one byte), the disc type ID is recorded.

Concerning a DVD-RAM, the physical information of the recording mediumis recorded in the embossed data area of the lead-in area. Accordingly,the disc drive unit is able to precisely and easily determine the discsize/configuration, the moment of inertia, the medium type, and so on.It is thus possible to provide suitable settings according to thephysical characteristics of the disc and perform the appropriaterecording/reading operation correspondingly.

7-3 DVD+RW

In a DVD+RW, which is a DVD-format rewritable disc using a phase-changerecording technique, various items of information are recorded on thedisc by a phase-modulated wobbling groove. Thus, the physicalcharacteristic information of the disc is included in ADIP informationwhich is to be recorded as the phase-modulated wobbling groove.

The phase-modulated wobbling information is described below withreference to FIGS. 66A, 66B, and 66C. Eight wobbles form one ADIP unit.The wobbles are then phase-modulated in such a manner that positivewobbles PW and negative wobbles NW are generated in a predeterminedorder. Accordingly, the ADIP unit represents a synchronization pattern,“0” data, or “1” data.

The head of the positive wobble PW directs toward the inner periphery ofthe disc, while the head of the negative wobble NW directs toward theouter periphery of the disc.

FIG. 66A illustrates the synchronization pattern (ADIP synchronizationunit). The first four wobbles (W0 through W3) are negative wobbles NW,and the last four wobbles (W4 through W7) are positive wobbles PW.

FIG. 66B illustrates the ADIP data unit indicating “0” data. The firstwobble W0 is a negative wobble NW, which serves as a bitsynchronization, and the subsequent three wobbles (W1 through W3) arepositive wobbles PW. In the last four wobbles, the two wobbles (W4 andW5) are positive wobbles PW, and the remaining two wobbles (W6 and W7)are negative wobbles NW. With this arrangement, the ADIP data represents“0” data.

FIG. 66C illustrates the ADIP data unit indicating “1” data. The firstwobble W0 is a negative wobble NW, which serves as a bitsynchronization, and the subsequent three wobbles (W1 through W3) arepositive wobbles PW. In the last four wobbles, the two wobbles (W4 andW5) are negative wobbles NW, and the remaining two wobbles (W6 and W7)are positive wobbles PW. With this arrangement, the ADIP data represents“1” data.

The data structure of the above-described ADIP units is as follows.

The ADIP unit information recorded as a wobbling groove is formed of twosynchronization frames as one unit shown in FIG. 67. The twosynchronization frames has 93 wobbles.

One wobble has 32 channel bits (32 T), and accordingly, onesynchronization frame is equal to 1488 channel bits. One ADIP unit isformed by eight phase-modulated wobbles among the two synchronizationframes (93 wobbles). The remaining 85 wobbles are monotone wobbles,which are not phase-modulated.

Fifty-two ADIP units form one ADIP word, which is equivalent to fourphysical sectors. The structure of the ADIP word is shown in FIG. 68A.

The ADIP word, which is formed of 52 ADIP units, each having eightwobbles (W0 through W7), has 52-bit information. The ADIP word consistsof one ADIP synchronization unit and 51 ADIP data units. Accordingly,among the 52 bits, as shown in FIG. 68A, data bit 1 to data bit 51 otherthan the word synchronization (data bit 0) can be used for recording51-bit information.

FIG. 68B illustrates the structure of the 52-bit ADIP word. Twenty-twobits from data bit 2 to data bit 23 are used for recording the physicaladdress. The physical address is provided for each ADIP word. Eight bitsfrom data bit 24 to data bit 31 are used for recording supplementaldata. Data bit 32 through data bit 51 are used as ECC data.

Concerning the eight-bit supplemental data for each ADIP word, 256supplemental data are collected from consecutive 256 ADIP data, therebyforming a 256-byte table. In such a table, the physical formatinformation, such as the one shown in FIG. 69A, can be recorded.

FIG. 69A illustrates only byte positions 0 to 30 among the 256 bytes,and the remaining bytes from byte positions 31 to 255 are not shown.

One byte at byte position 0 is used for recording the disc category andthe version number. One byte at byte position 1 is used for recordingthe disc size. One byte at byte position 2 is used for recording thedisc structure. One byte at byte position 3 is used for recording therecording density. Twelve bytes at byte positions 4 through 15 are usedfor recording the data zone allocation. One byte at byte position 17 isused for recording the moment of inertia and the disc configuration.

At byte position 17, for example, as shown in FIG. 69B, two bits b7 andb6 are used for recording the moment of inertia, and two bits b5 and b4are used for recording the disc configuration.

When bits b7 and b6 are represented by J1 and J2, respectively, themoment of inertia can be defined as shown in FIG. 60B. The discconfiguration information can be recorded by the definition shown inFIG. 34 by using the two bits b5 and b4.

As discussed above, in the case of a DVD+RW, the physical information ofthe disc is recorded as a phase-modulated wobbling groove. This enablesa disc drive unit to correctly and easily determine the disc size, thedisc configuration, the moment of inertia, the medium type, etc. As aresult, it is possible to perform suitable settings according to thephysical characteristics and thus to perform an appropriaterecording/reading operation correspondingly.

While the present invention has been described with reference to whatare presently considered to be the preferred embodiment, variousmodifications may be made to the configuration of the disc drive unit,the operations of the unit, the structure of the wobble information, thestructure of the sub-Q data, etc.

What is claimed is:
 1. A recording medium comprising main data and asub-code recorded therein, wherein physical characteristic informationof said recording medium is recorded within said sub-code, saidrecording medium further comprising point information representingcontent types of predetermined information disposed within saidsub-code, and said physical characteristic information is recorded incorrespondence with specific values of the point information.
 2. Arecording medium comprising main data and a sub-code recorded therein,wherein physical characteristic information of said recording medium isrecorded within said sub-code, wherein said physical characteristicinformation comprises information concerning a material of saidrecording medium.
 3. A recording medium comprising main data and asub-code recorded therein, wherein physical characteristic informationof said recording medium is recorded within said sub-code, wherein saidphysical characteristic information comprises information concerning alinear velocity of said recording medium.
 4. A recording mediumcomprising main data and a sub-code recorded therein, wherein physicalcharacteristic information of said recording medium is recorded withinsaid sub-code, wherein said physical characteristic informationcomprises information concerning a track pitch of said recording medium.5. A recording medium comprising main data and a sub-code recordedtherein, wherein physical characteristic information of said recordingmedium is recorded within said sub-code, wherein said physicalcharacteristics information comprises information concerning a moment ofinertia of said recording medium.
 6. A recording medium comprising maindata and a sub-code recorded therein, wherein physical characteristicinformation of said recording medium is recorded within said sub-code,wherein said physical characteristics information comprises informationconcerning at least one of a configuration and a size of said recordingmedium.
 7. A recording medium for storing main data and a sub-code, saidrecording medium comprising a plurality of recording/reading unit areaswhose physical characteristics are different, each of saidrecording/reading unit areas consisting of a lead-in area, a programarea, and a lead-out area, wherein, in the sub-code of the lead-in areaof each of said recording/reading unit areas, physical characteristicinformation of the corresponding recording/reading unit area isrecorded, and start position information indicating a position at whichthe lead-in area of the subsequent recording/reading unit area starts isrecorded.
 8. A recording medium according to claim 7, wherein, in thesub-code of the lead-in area of each of said recording/reading unitareas, end position information indicating a position at which thelead-out area of the corresponding recording/reading unit area ends isrecorded.
 9. A recording medium according to claim 7, wherein thesub-code is recorded in a CD format.
 10. A recording apparatuscompatible with a recording medium which stores main data and asub-code, said recording medium comprising a plurality ofrecording/reading unit areas whose physical characteristics aredifferent, each of said recording/reading unit areas consisting of alead-in area, a program area, and a lead-out area, wherein, in saidsub-code of the lead-in area of each of said recording/reading unitareas, physical characteristic information of the correspondingrecording/reading unit area is recorded, and start position informationindicating a position at which the lead-in area of the subsequentrecording/reading unit area starts is recorded, said recording apparatuscomprising: access control means for determining the position of thelead-in area of the subsequent recording/reading unit area from thestart position information recorded in the lead-in area of the currentrecording/reading unit area, and for allowing access to the determinedposition; determining means for reading the physical characteristicinformation from the lead-in area of each of the recording/reading unitareas in accordance with the access controlled by said access controlmeans, and for determining the physical characteristics of thecorresponding recording/reading unit area; and recording control meansfor performing settings for a recording operation for each of therecording/reading unit areas according to the physical characteristicsdetermined by said determining means and for allowing the recordingoperation to be performed.
 11. A recording apparatus according to claim10, wherein said sub-code is recorded on said recording medium in a CDformat.
 12. A reading apparatus compatible with a recording medium whichstores main data and a sub-code, said recording medium comprising aplurality of recording/reading unit areas whose physical characteristicsare different, each of said recording/reading unit areas consisting of alead-in area, a program area, and a lead-out area, wherein, in saidsub-code of the lead-in area of each of said recording/reading unitareas, physical characteristic information of the correspondingrecording/reading unit area is recorded, and start position informationindicating a position at which the lead-in area of the subsequentrecording/reading unit area starts is recorded, said reading apparatuscomprising: access control means for determining the position of thelead-in area of the subsequent recording/reading unit area from thestart position information recorded in the lead-in area of the currentrecording/reading unit area, and for allowing access to the determinedposition; determining means for reading the physical characteristicinformation from the lead-in area of each of the recording/reading unitareas in accordance with the access controlled by said access controlmeans, and for determining the physical characteristics of thecorresponding recording/reading unit area; and reading control means forperforming settings for a reading operation for each of therecording/reading unit areas according to the physical characteristicsdetermined by said determining means and for allowing the readingoperation to be performed.
 13. A reading apparatus according to claim12, wherein said sub-code is recorded on said recording medium in a CDformat.